31920289 has 4 divisors (see below), whose sum is σ = 31948720. Its totient is φ = 31891860.

The previous prime is 31920269. The next prime is 31920293. The reversal of 31920289 is 98202913.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 98202913 = 41 ⋅2395193.

It is a cyclic number.

It is not a de Polignac number, because 31920289 - 2⁹ = 31919777 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31920269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12459 + ... + 14800.

It is an arithmetic number, because the mean of its divisors is an integer number (7987180).

Almost surely, 2^31920289 is an apocalyptic number.

It is an amenable number.

31920289 is a deficient number, since it is larger than the sum of its proper divisors (28431).

31920289 is a wasteful number, since it uses less digits than its factorization.

31920289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28430.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 31920289 is about 5649.8043328951. The cubic root of 31920289 is about 317.2163801136.

The spelling of 31920289 in words is "thirty-one million, nine hundred twenty thousand, two hundred eighty-nine".