39979840 has 56 divisors (see below), whose sum is σ = 96222312. Its totient is φ = 15820800.

The previous prime is 39979831. The next prime is 39979843. The reversal of 39979840 is 4897993.

It can be written as a sum of positive squares in 4 ways, for example, as 18524416 + 21455424 = 4304^2 + 4632^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (39979843) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31702 + ... + 32938.

Almost surely, 2^39979840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 39979840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48111156).

39979840 is an abundant number, since it is smaller than the sum of its proper divisors (56242472).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

39979840 is a wasteful number, since it uses less digits than its factorization.

39979840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1355 (or 1345 counting only the distinct ones).

The product of its (nonzero) digits is 489888, while the sum is 49.

The square root of 39979840 is about 6322.9613315281. The cubic root of 39979840 is about 341.9377244884.

The spelling of 39979840 in words is "thirty-nine million, nine hundred seventy-nine thousand, eight hundred forty".