20931869 has 6 divisors (see below), whose sum is σ = 24349374. Its totient is φ = 17941560.

The previous prime is 20931809. The next prime is 20931877. The reversal of 20931869 is 96813902.

It can be written as a sum of positive squares in only one way, i.e., 12694969 + 8236900 = 3563^2 + 2870^2 .

It is a de Polignac number, because none of the positive numbers 2^k-20931869 is a prime.

It is a super-2 number, since 2×20931869² = 876286279666322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 213542 + ... + 213639.

It is an arithmetic number, because the mean of its divisors is an integer number (4058229).

Almost surely, 2^20931869 is an apocalyptic number.

It is an amenable number.

20931869 is a deficient number, since it is larger than the sum of its proper divisors (3417505).

20931869 is an equidigital number, since it uses as much as digits as its factorization.

20931869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 427195 (or 427188 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 38.

The square root of 20931869 is about 4575.1359542641. The cubic root of 20931869 is about 275.5937320707.

The spelling of 20931869 in words is "twenty million, nine hundred thirty-one thousand, eight hundred sixty-nine".