3656213131221 has 12 divisors (see below), whose sum is σ = 6035653423072. Its totient is φ = 2089264646376.

The previous prime is 3656213131217. The next prime is 3656213131229. The reversal of 3656213131221 is 1221313126563.

3656213131221 is a `hidden beast` number, since 3 + 6 + 5 + 621 + 3 + 1 + 3 + 1 + 2 + 21 = 666.

3656213131221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 3656213131221 - 2² = 3656213131217 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3656213131229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29017564471 + ... + 29017564596.

Almost surely, 2^{3656213131221} is an apocalyptic number.

It is an amenable number.

3656213131221 is a deficient number, since it is larger than the sum of its proper divisors (2379440291851).

3656213131221 is a wasteful number, since it uses less digits than its factorization.

3656213131221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58035129080 (or 58035129077 counting only the distinct ones).

The product of its digits is 38880, while the sum is 36.

Adding to 3656213131221 its reverse (1221313126563), we get a palindrome (4877526257784).

The spelling of 3656213131221 in words is "three trillion, six hundred fifty-six billion, two hundred thirteen million, one hundred thirty-one thousand, two hundred twenty-one".