3656209921 has 24 divisors (see below), whose sum is σ = 4589815104. Its totient is φ = 2886821280.

The previous prime is 3656209897. The next prime is 3656209933. The reversal of 3656209921 is 1299026563.

3656209921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 3656209921 - 2¹⁵ = 3656177153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (3656209951) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 314706 + ... + 326116.

It is an arithmetic number, because the mean of its divisors is an integer number (191242296).

Almost surely, 2^3656209921 is an apocalyptic number.

It is an amenable number.

3656209921 is a deficient number, since it is larger than the sum of its proper divisors (933605183).

3656209921 is a wasteful number, since it uses less digits than its factorization.

3656209921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11941 (or 11934 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 43.

The square root of 3656209921 is about 60466.6016987891. The cubic root of 3656209921 is about 1540.5544078244.

The spelling of 3656209921 in words is "three billion, six hundred fifty-six million, two hundred nine thousand, nine hundred twenty-one".