861638721672960 has 2592 divisors, whose sum is σ = 3937584293959680. Its totient is φ = 168975640166400.

The previous prime is 861638721672959. The next prime is 861638721672983. The reversal of 861638721672960 is 69276127836168.

861638721672960 is a `hidden beast` number, since 8 + 6 + 1 + 6 + 387 + 2 + 167 + 29 + 60 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 287 ways as a sum of consecutive naturals, for example, 86780005276 + ... + 86780015204.

It is an arithmetic number, because the mean of its divisors is an integer number (1519129743040).

Almost surely, 2^{861638721672960} is an apocalyptic number.

861638721672960 is a gapful number since it is divisible by the number (80) 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 861638721672960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1968792146979840).

861638721672960 is an abundant number, since it is smaller than the sum of its proper divisors (3075945572286720).

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

861638721672960 is a wasteful number, since it uses less digits than its factorization.

861638721672960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10283 (or 10247 counting only the distinct ones).

The product of its (nonzero) digits is 438939648, while the sum is 72.

The spelling of 861638721672960 in words is "eight hundred sixty-one trillion, six hundred thirty-eight billion, seven hundred twenty-one million, six hundred seventy-two thousand, nine hundred sixty".