3900815621 has 16 divisors (see below), whose sum is σ = 4021617600. Its totient is φ = 3782064000.

The previous prime is 3900815603. The next prime is 3900815669. The reversal of 3900815621 is 1265180093.

3900815621 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 3900815621 - 2¹⁸ = 3900553477 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3900815671) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2997671 + ... + 2998971.

It is an arithmetic number, because the mean of its divisors is an integer number (251351100).

Almost surely, 2^3900815621 is an apocalyptic number.

It is an amenable number.

3900815621 is a deficient number, since it is larger than the sum of its proper divisors (120801979).

3900815621 is a wasteful number, since it uses less digits than its factorization.

3900815621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2020.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 3900815621 is about 62456.5098368457. The cubic root of 3900815621 is about 1574.1706386529.

The spelling of 3900815621 in words is "three billion, nine hundred million, eight hundred fifteen thousand, six hundred twenty-one".