1261947435840 has 448 divisors, whose sum is σ = 5479228177920. Its totient is φ = 266256875520.

The previous prime is 1261947435839. The next prime is 1261947435871. The reversal of 1261947435840 is 485347491621.

1261947435840 is a `hidden beast` number, since 1 + 2 + 6 + 19 + 4 + 7 + 43 + 584 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a super-2 number, since 2×1261947435840² (a number of 25 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 16281 + ... + 1588760.

It is an arithmetic number, because the mean of its divisors is an integer number (12230420040).

It is a 2-persistent number, because it is pandigital, and so is 2⋅1261947435840 = 2523894871680, but 3⋅1261947435840 = 3785842307520 is not.

Almost surely, 2^{1261947435840} is an apocalyptic number.

1261947435840 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261947435840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2739614088960).

1261947435840 is an abundant number, since it is smaller than the sum of its proper divisors (4217280742080).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1261947435840 is a wasteful number, since it uses less digits than its factorization.

1261947435840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1605087 (or 1605071 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 54.

The spelling of 1261947435840 in words is "one trillion, two hundred sixty-one billion, nine hundred forty-seven million, four hundred thirty-five thousand, eight hundred forty".