39665978 has 12 divisors (see below), whose sum is σ = 65400090. Its totient is φ = 18029880.

The previous prime is 39665971. The next prime is 39666001. The reversal of 39665978 is 87956693.

It can be written as a sum of positive squares in only one way, i.e., 33097009 + 6568969 = 5753^2 + 2563^2 .

It is not an unprimeable number, because it can be changed into a prime (39665971) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 81713 + ... + 82196.

Almost surely, 2^39665978 is an apocalyptic number.

39665978 is a deficient number, since it is larger than the sum of its proper divisors (25734112).

39665978 is a wasteful number, since it uses less digits than its factorization.

39665978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163933 (or 163922 counting only the distinct ones).

The product of its digits is 2449440, while the sum is 53.

The square root of 39665978 is about 6298.0932035022. The cubic root of 39665978 is about 341.0405778975.

The spelling of 39665978 in words is "thirty-nine million, six hundred sixty-five thousand, nine hundred seventy-eight".