21372165361 has 4 divisors (see below), whose sum is σ = 21430400512. Its totient is φ = 21313930212.

The previous prime is 21372165239. The next prime is 21372165433. The reversal of 21372165361 is 16356127312.

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 21372165361 - 2⁷ = 21372165233 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 21372165361.

It is not an unprimeable number, because it can be changed into a prime (21372163361) 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, 29117025 + ... + 29117758.

It is an arithmetic number, because the mean of its divisors is an integer number (5357600128).

Almost surely, 2^21372165361 is an apocalyptic number.

It is an amenable number.

21372165361 is a deficient number, since it is larger than the sum of its proper divisors (58235151).

21372165361 is an equidigital number, since it uses as much as digits as its factorization.

21372165361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58235150.

The product of its digits is 45360, while the sum is 37.

The spelling of 21372165361 in words is "twenty-one billion, three hundred seventy-two million, one hundred sixty-five thousand, three hundred sixty-one".