3656421221 has 2 divisors, whose sum is σ = 3656421222. Its totient is φ = 3656421220.

The previous prime is 3656421169. The next prime is 3656421247. The reversal of 3656421221 is 1221246563.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2569070596 + 1087350625 = 50686^2 + 32975^2 .

It is a cyclic number.

It is not a de Polignac number, because 3656421221 - 2²² = 3652226917 is a prime.

It is a super-2 number, since 2×3656421221² = 26738832290758261682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3656421121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1828210610 + 1828210611.

It is an arithmetic number, because the mean of its divisors is an integer number (1828210611).

Almost surely, 2^3656421221 is an apocalyptic number.

It is an amenable number.

3656421221 is a deficient number, since it is larger than the sum of its proper divisors (1).

3656421221 is an equidigital number, since it uses as much as digits as its factorization.

3656421221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17280, while the sum is 32.

The square root of 3656421221 is about 60468.3489190833. The cubic root of 3656421221 is about 1540.5840845373.

Adding to 3656421221 its reverse (1221246563), we get a palindrome (4877667784).

The spelling of 3656421221 in words is "three billion, six hundred fifty-six million, four hundred twenty-one thousand, two hundred twenty-one".