39979987 has 4 divisors (see below), whose sum is σ = 41269696. Its totient is φ = 38690280.

The previous prime is 39979969. The next prime is 39979997. The reversal of 39979987 is 78997993.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 39979987 - 2⁷ = 39979859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (39979997) 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, 644808 + ... + 644869.

It is an arithmetic number, because the mean of its divisors is an integer number (10317424).

Almost surely, 2^39979987 is an apocalyptic number.

39979987 is a deficient number, since it is larger than the sum of its proper divisors (1289709).

39979987 is a wasteful number, since it uses less digits than its factorization.

39979987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289708.

The product of its digits is 7715736, while the sum is 61.

The square root of 39979987 is about 6322.9729558175. The cubic root of 39979987 is about 341.9381435728.

The spelling of 39979987 in words is "thirty-nine million, nine hundred seventy-nine thousand, nine hundred eighty-seven".