3999936521 has 4 divisors (see below), whose sum is σ = 4571356032. Its totient is φ = 3428517012.

The previous prime is 3999936517. The next prime is 3999936547. The reversal of 3999936521 is 1256399993.

3999936521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 3999936521 - 2² = 3999936517 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3999636521) 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, 285709745 + ... + 285709758.

It is an arithmetic number, because the mean of its divisors is an integer number (1142839008).

Almost surely, 2^3999936521 is an apocalyptic number.

It is an amenable number.

3999936521 is a deficient number, since it is larger than the sum of its proper divisors (571419511).

3999936521 is an equidigital number, since it uses as much as digits as its factorization.

3999936521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 571419510.

The product of its digits is 3542940, while the sum is 56.

The square root of 3999936521 is about 63245.0513558176. The cubic root of 3999936521 is about 1587.3926547045.

The spelling of 3999936521 in words is "three billion, nine hundred ninety-nine million, nine hundred thirty-six thousand, five hundred twenty-one".