31665379920 has 160 divisors (see below), whose sum is σ = 99232898688. Its totient is φ = 8352497664.

The previous prime is 31665379903. The next prime is 31665379931. The reversal of 31665379920 is 2997356613.

It is a happy number.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10092592 + ... + 10095728.

Almost surely, 2^31665379920 is an apocalyptic number.

31665379920 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31665379920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49616449344).

31665379920 is an abundant number, since it is smaller than the sum of its proper divisors (67567518768).

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

31665379920 is a wasteful number, since it uses less digits than its factorization.

31665379920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3597 (or 3591 counting only the distinct ones).

The product of its (nonzero) digits is 1837080, while the sum is 51.

The spelling of 31665379920 in words is "thirty-one billion, six hundred sixty-five million, three hundred seventy-nine thousand, nine hundred twenty".