39720639 has 16 divisors (see below), whose sum is σ = 60730112. Its totient is φ = 22621248.

The previous prime is 39720623. The next prime is 39720643. The reversal of 39720639 is 93602793.

It is not a de Polignac number, because 39720639 - 2⁴ = 39720623 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 39720597 and 39720606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39720679) 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, 3552 + ... + 9594.

It is an arithmetic number, because the mean of its divisors is an integer number (3795632).

Almost surely, 2^39720639 is an apocalyptic number.

39720639 is a deficient number, since it is larger than the sum of its proper divisors (21009473).

39720639 is a wasteful number, since it uses less digits than its factorization.

39720639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6366.

The product of its (nonzero) digits is 61236, while the sum is 39.

The square root of 39720639 is about 6302.4311975618. The cubic root of 39720639 is about 341.1971609745.

The spelling of 39720639 in words is "thirty-nine million, seven hundred twenty thousand, six hundred thirty-nine".