21320661356 has 12 divisors (see below), whose sum is σ = 37312619400. Its totient is φ = 10659912960.

The previous prime is 21320661353. The next prime is 21320661413. The reversal of 21320661356 is 65316602312.

It is not an unprimeable number, because it can be changed into a prime (21320661353) 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, 29495 + ... + 208593.

It is an arithmetic number, because the mean of its divisors is an integer number (3109384950).

Almost surely, 2^21320661356 is an apocalyptic number.

It is an amenable number.

21320661356 is a deficient number, since it is larger than the sum of its proper divisors (15991958044).

21320661356 is a wasteful number, since it uses less digits than its factorization.

21320661356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 208864 (or 208862 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 35.

The spelling of 21320661356 in words is "twenty-one billion, three hundred twenty million, six hundred sixty-one thousand, three hundred fifty-six".