261312451920 has 320 divisors, whose sum is σ = 976402506240. Its totient is φ = 63852613632.

The previous prime is 261312451909. The next prime is 261312451927. The reversal of 261312451920 is 29154213162.

261312451920 is a `hidden beast` number, since 2 + 6 + 13 + 124 + 519 + 2 + 0 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261312451927) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3812997 + ... + 3880923.

It is an arithmetic number, because the mean of its divisors is an integer number (3051257832).

Almost surely, 2^261312451920 is an apocalyptic number.

261312451920 is a gapful number since it is divisible by the number (20) 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 261312451920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (488201253120).

261312451920 is an abundant number, since it is smaller than the sum of its proper divisors (715090054320).

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

261312451920 is a wasteful number, since it uses less digits than its factorization.

261312451920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68099 (or 68087 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The spelling of 261312451920 in words is "two hundred sixty-one billion, three hundred twelve million, four hundred fifty-one thousand, nine hundred twenty".