1261261872640 has 960 divisors, whose sum is σ = 3970745856000. Its totient is φ = 375756226560.

The previous prime is 1261261872589. The next prime is 1261261872641. The reversal of 1261261872640 is 462781621621.

It is a super-2 number, since 2×1261261872640² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261261872641) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 6337999261 + ... + 6337999459.

It is an arithmetic number, because the mean of its divisors is an integer number (4136193600).

Almost surely, 2^{1261261872640} is an apocalyptic number.

1261261872640 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 1261261872640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1985372928000).

1261261872640 is an abundant number, since it is smaller than the sum of its proper divisors (2709483983360).

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

1261261872640 is a wasteful number, since it uses less digits than its factorization.

1261261872640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 367 (or 340 counting only the distinct ones).

The product of its (nonzero) digits is 387072, while the sum is 46.

The spelling of 1261261872640 in words is "one trillion, two hundred sixty-one billion, two hundred sixty-one million, eight hundred seventy-two thousand, six hundred forty".