31920399 has 40 divisors (see below), whose sum is σ = 57383040. Its totient is φ = 17274384.

The previous prime is 31920391. The next prime is 31920409. The reversal of 31920399 is 99302913.

It is not a de Polignac number, because 31920399 - 2³ = 31920391 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31920391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 9292 + ... + 12254.

It is an arithmetic number, because the mean of its divisors is an integer number (1434576).

Almost surely, 2^31920399 is an apocalyptic number.

31920399 is a deficient number, since it is larger than the sum of its proper divisors (25462641).

31920399 is a wasteful number, since it uses less digits than its factorization.

31920399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3001 (or 2992 counting only the distinct ones).

The product of its (nonzero) digits is 13122, while the sum is 36.

The square root of 31920399 is about 5649.8140677371. The cubic root of 31920399 is about 317.2167444980.

The spelling of 31920399 in words is "thirty-one million, nine hundred twenty thousand, three hundred ninety-nine".