21167214721 has 4 divisors (see below), whose sum is σ = 21167509552. Its totient is φ = 21166919892.

The previous prime is 21167214707. The next prime is 21167214751. The reversal of 21167214721 is 12741276112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21167214721 - 2²⁷ = 21032996993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21167214751) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38086 + ... + 209248.

It is an arithmetic number, because the mean of its divisors is an integer number (5291877388).

Almost surely, 2^21167214721 is an apocalyptic number.

It is an amenable number.

21167214721 is a deficient number, since it is larger than the sum of its proper divisors (294831).

21167214721 is a wasteful number, since it uses less digits than its factorization.

21167214721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294830.

The product of its digits is 9408, while the sum is 34.

The spelling of 21167214721 in words is "twenty-one billion, one hundred sixty-seven million, two hundred fourteen thousand, seven hundred twenty-one".