15978558921 has 16 divisors (see below), whose sum is σ = 23095524480. Its totient is φ = 9767836800.

The previous prime is 15978558863. The next prime is 15978558941. The reversal of 15978558921 is 12985587951.

It is not a de Polignac number, because 15978558921 - 2⁷ = 15978558793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (15978558941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1350756 + ... + 1362533.

It is an arithmetic number, because the mean of its divisors is an integer number (1443470280).

Almost surely, 2^15978558921 is an apocalyptic number.

It is an amenable number.

15978558921 is a deficient number, since it is larger than the sum of its proper divisors (7116965559).

15978558921 is a wasteful number, since it uses less digits than its factorization.

15978558921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2713456.

The product of its digits is 9072000, while the sum is 60.

The spelling of 15978558921 in words is "fifteen billion, nine hundred seventy-eight million, five hundred fifty-eight thousand, nine hundred twenty-one".