191631920256 has 320 divisors, whose sum is σ = 669388610880. Its totient is φ = 53271447552.

The previous prime is 191631920251. The next prime is 191631920287. The reversal of 191631920256 is 652029136191.

191631920256 is a `hidden beast` number, since 1 + 9 + 1 + 631 + 9 + 2 + 0 + 2 + 5 + 6 = 666.

It is a super-2 number, since 2×191631920256² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (191631920251) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2649631 + ... + 2720993.

It is an arithmetic number, because the mean of its divisors is an integer number (2091839409).

Almost surely, 2^191631920256 is an apocalyptic number.

191631920256 is a gapful number since it is divisible by the number (16) 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 191631920256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (334694305440).

191631920256 is an abundant number, since it is smaller than the sum of its proper divisors (477756690624).

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

191631920256 is an equidigital number, since it uses as much as digits as its factorization.

191631920256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71433 (or 71412 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 45.

The spelling of 191631920256 in words is "one hundred ninety-one billion, six hundred thirty-one million, nine hundred twenty thousand, two hundred fifty-six".