20291931 has 32 divisors (see below), whose sum is σ = 34732800. Its totient is φ = 11571840.

The previous prime is 20291903. The next prime is 20291969. The reversal of 20291931 is 13919202.

It is not a de Polignac number, because 20291931 - 2¹⁴ = 20275547 is a prime.

It is a super-2 number, since 2×20291931² = 823524927417522, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 20291895 and 20291904.

It is not an unprimeable number, because it can be changed into a prime (20291231) 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 31 ways as a sum of consecutive naturals, for example, 3040 + ... + 7058.

It is an arithmetic number, because the mean of its divisors is an integer number (1085400).

Almost surely, 2^20291931 is an apocalyptic number.

20291931 is a deficient number, since it is larger than the sum of its proper divisors (14440869).

20291931 is a wasteful number, since it uses less digits than its factorization.

20291931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4056 (or 4050 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 20291931 is about 4504.6565906848. The cubic root of 20291931 is about 272.7560917728.

The spelling of 20291931 in words is "twenty million, two hundred ninety-one thousand, nine hundred thirty-one".