21664604611 has 4 divisors (see below), whose sum is σ = 23331112672. Its totient is φ = 19998096552.

The previous prime is 21664604587. The next prime is 21664604629. The reversal of 21664604611 is 11640646612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21664604611 - 2²¹ = 21662507459 is a prime.

It is a super-2 number, since 2×21664604611² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21664604641) by changing a digit.

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, 833254011 + ... + 833254036.

It is an arithmetic number, because the mean of its divisors is an integer number (5832778168).

Almost surely, 2^21664604611 is an apocalyptic number.

21664604611 is a deficient number, since it is larger than the sum of its proper divisors (1666508061).

21664604611 is a wasteful number, since it uses less digits than its factorization.

21664604611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1666508060.

The product of its (nonzero) digits is 41472, while the sum is 37.

The spelling of 21664604611 in words is "twenty-one billion, six hundred sixty-four million, six hundred four thousand, six hundred eleven".