21516164257 has 24 divisors (see below), whose sum is σ = 26874633600. Its totient is φ = 17113057920.

The previous prime is 21516164251. The next prime is 21516164273. The reversal of 21516164257 is 75246161512.

It is not a de Polignac number, because 21516164257 - 2³ = 21516164249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21516164251) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 122757 + ... + 241042.

It is an arithmetic number, because the mean of its divisors is an integer number (1119776400).

Almost surely, 2^21516164257 is an apocalyptic number.

It is an amenable number.

21516164257 is a deficient number, since it is larger than the sum of its proper divisors (5358469343).

21516164257 is a wasteful number, since it uses less digits than its factorization.

21516164257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 363901 (or 363894 counting only the distinct ones).

The product of its digits is 100800, while the sum is 40.

The spelling of 21516164257 in words is "twenty-one billion, five hundred sixteen million, one hundred sixty-four thousand, two hundred fifty-seven".