21164265671 has 4 divisors (see below), whose sum is σ = 21171076200. Its totient is φ = 21157455144.

The previous prime is 21164265613. The next prime is 21164265673. The reversal of 21164265671 is 17656246112.

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 21164265671 - 2¹⁸ = 21164003527 is a prime.

It is a super-2 number, since 2×21164265671² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164265673) 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 3 ways as a sum of consecutive naturals, for example, 3400601 + ... + 3406818.

It is an arithmetic number, because the mean of its divisors is an integer number (5292769050).

Almost surely, 2^21164265671 is an apocalyptic number.

21164265671 is a deficient number, since it is larger than the sum of its proper divisors (6810529).

21164265671 is an equidigital number, since it uses as much as digits as its factorization.

21164265671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6810528.

The product of its digits is 120960, while the sum is 41.

The spelling of 21164265671 in words is "twenty-one billion, one hundred sixty-four million, two hundred sixty-five thousand, six hundred seventy-one".