39872721 has 16 divisors (see below), whose sum is σ = 62000000. Its totient is φ = 22783824.

The previous prime is 39872713. The next prime is 39872737. The reversal of 39872721 is 12727893.

It is not a de Polignac number, because 39872721 - 2³ = 39872713 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 39872721.

It is not an unprimeable number, because it can be changed into a prime (39872741) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18346 + ... + 20403.

It is an arithmetic number, because the mean of its divisors is an integer number (3875000).

Almost surely, 2^39872721 is an apocalyptic number.

It is an amenable number.

39872721 is a deficient number, since it is larger than the sum of its proper divisors (22127279).

39872721 is an equidigital number, since it uses as much as digits as its factorization.

39872721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38773 (or 38759 counting only the distinct ones).

The product of its digits is 42336, while the sum is 39.

The square root of 39872721 is about 6314.4850146310. The cubic root of 39872721 is about 341.6320638630.

The spelling of 39872721 in words is "thirty-nine million, eight hundred seventy-two thousand, seven hundred twenty-one".