39609981 has 12 divisors (see below), whose sum is σ = 57430620. Its totient is φ = 26306880.

The previous prime is 39609967. The next prime is 39609991. The reversal of 39609981 is 18990693.

39609981 is a `hidden beast` number, since 39 + 609 + 9 + 8 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7868025 + 31741956 = 2805^2 + 5634^2 .

It is not a de Polignac number, because 39609981 - 2⁶ = 39609917 is a prime.

It is a super-2 number, since 2×39609981² = 3137901189640722, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39609961) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5760 + ... + 10601.

It is an arithmetic number, because the mean of its divisors is an integer number (4785885).

Almost surely, 2^39609981 is an apocalyptic number.

It is an amenable number.

39609981 is a deficient number, since it is larger than the sum of its proper divisors (17820639).

39609981 is a wasteful number, since it uses less digits than its factorization.

39609981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16636 (or 16633 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The square root of 39609981 is about 6293.6460815651. The cubic root of 39609981 is about 340.8800184469.

The spelling of 39609981 in words is "thirty-nine million, six hundred nine thousand, nine hundred eighty-one".