21266251916 has 24 divisors (see below), whose sum is σ = 45804235680. Its totient is φ = 8413022592.

The previous prime is 21266251907. The next prime is 21266251933. The reversal of 21266251916 is 61915266212.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29211521 + ... + 29212248.

It is an arithmetic number, because the mean of its divisors is an integer number (1908509820).

Almost surely, 2^21266251916 is an apocalyptic number.

21266251916 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21266251916 is an abundant number, since it is smaller than the sum of its proper divisors (24537983764).

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

21266251916 is a wasteful number, since it uses less digits than its factorization.

21266251916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58423793 (or 58423791 counting only the distinct ones).

The product of its digits is 77760, while the sum is 41.

The spelling of 21266251916 in words is "twenty-one billion, two hundred sixty-six million, two hundred fifty-one thousand, nine hundred sixteen".