21216404165153 has 4 divisors (see below), whose sum is σ = 21472023492528. Its totient is φ = 20960784837780.

The previous prime is 21216404165147. The next prime is 21216404165171. The reversal of 21216404165153 is 35156140461212.

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.

It is a cyclic number.

It is not a de Polignac number, because 21216404165153 - 2³² = 21212109197857 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21216404165153.

It is not an unprimeable number, because it can be changed into a prime (21216404165053) 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, 127809663563 + ... + 127809663728.

It is an arithmetic number, because the mean of its divisors is an integer number (5368005873132).

Almost surely, 2^{21216404165153} is an apocalyptic number.

It is an amenable number.

21216404165153 is a deficient number, since it is larger than the sum of its proper divisors (255619327375).

21216404165153 is an equidigital number, since it uses as much as digits as its factorization.

21216404165153 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 255619327374.

The product of its (nonzero) digits is 172800, while the sum is 41.

The spelling of 21216404165153 in words is "twenty-one trillion, two hundred sixteen billion, four hundred four million, one hundred sixty-five thousand, one hundred fifty-three".