1261761840 has 160 divisors (see below), whose sum is σ = 4359096000. Its totient is φ = 335462400.

The previous prime is 1261761829. The next prime is 1261761847. The reversal of 1261761840 is 481671621.

It is a happy number.

1261761840 is a `hidden beast` number, since 1 + 26 + 17 + 618 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1261761795 and 1261761804.

It is not an unprimeable number, because it can be changed into a prime (1261761847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 969190 + ... + 970490.

It is an arithmetic number, because the mean of its divisors is an integer number (27244350).

Almost surely, 2^1261761840 is an apocalyptic number.

1261761840 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 1261761840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2179548000).

1261761840 is an abundant number, since it is smaller than the sum of its proper divisors (3097334160).

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

1261761840 is a wasteful number, since it uses less digits than its factorization.

1261761840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1772 (or 1760 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 36.

The square root of 1261761840 is about 35521.2871388411. The cubic root of 1261761840 is about 1080.5854850111.

The spelling of 1261761840 in words is "one billion, two hundred sixty-one million, seven hundred sixty-one thousand, eight hundred forty".