20688831 has 16 divisors (see below), whose sum is σ = 30925920. Its totient is φ = 13668480.

The previous prime is 20688827. The next prime is 20688869. The reversal of 20688831 is 13888602.

It is not a de Polignac number, because 20688831 - 2² = 20688827 is a prime.

It is a super-2 number, since 2×20688831² = 856055456293122, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20688931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 340 + ... + 6441.

It is an arithmetic number, because the mean of its divisors is an integer number (1932870).

Almost surely, 2^20688831 is an apocalyptic number.

20688831 is a deficient number, since it is larger than the sum of its proper divisors (10237089).

20688831 is a wasteful number, since it uses less digits than its factorization.

20688831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6903 (or 6897 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 20688831 is about 4548.4976640645. The cubic root of 20688831 is about 274.5229459155.

The spelling of 20688831 in words is "twenty million, six hundred eighty-eight thousand, eight hundred thirty-one".