21106564764 has 12 divisors (see below), whose sum is σ = 49248651144. Its totient is φ = 7035521584.

The previous prime is 21106564741. The next prime is 21106564819. The reversal of 21106564764 is 46746560112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21106564764² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 879440187 + ... + 879440210.

It is an arithmetic number, because the mean of its divisors is an integer number (4104054262).

Almost surely, 2^21106564764 is an apocalyptic number.

It is an amenable number.

21106564764 is an abundant number, since it is smaller than the sum of its proper divisors (28142086380).

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

21106564764 is a wasteful number, since it uses less digits than its factorization.

21106564764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1758880404 (or 1758880402 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 42.

The spelling of 21106564764 in words is "twenty-one billion, one hundred six million, five hundred sixty-four thousand, seven hundred sixty-four".