115991601921 has 48 divisors (see below), whose sum is σ = 188440027776. Its totient is φ = 68216594688.

The previous prime is 115991601917. The next prime is 115991601959. The reversal of 115991601921 is 129106199511.

It is a happy number.

115991601921 is a `hidden beast` number, since 1 + 15 + 9 + 9 + 1 + 601 + 9 + 21 = 666.

It is not a de Polignac number, because 115991601921 - 2² = 115991601917 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (115991601961) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3176061 + ... + 3212373.

It is an arithmetic number, because the mean of its divisors is an integer number (3925833912).

Almost surely, 2^115991601921 is an apocalyptic number.

It is an amenable number.

115991601921 is a deficient number, since it is larger than the sum of its proper divisors (72448425855).

115991601921 is a wasteful number, since it uses less digits than its factorization.

115991601921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37542 (or 37539 counting only the distinct ones).

The product of its (nonzero) digits is 43740, while the sum is 45.

The spelling of 115991601921 in words is "one hundred fifteen billion, nine hundred ninety-one million, six hundred one thousand, nine hundred twenty-one".