21869631 has 36 divisors (see below), whose sum is σ = 37186344. Its totient is φ = 12348000.

The previous prime is 21869609. The next prime is 21869641. The reversal of 21869631 is 13696812.

21869631 = 91³ + 92³ + ... + 111³.

21869631 is a `hidden beast` number, since 2 + 18 + 6 + 9 + 631 = 666.

It is not a de Polignac number, because 21869631 - 2⁹ = 21869119 is a prime.

It is a super-2 number, since 2×21869631² = 956561520152322, 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 (21869641) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 44296 + ... + 44786.

It is an arithmetic number, because the mean of its divisors is an integer number (1032954).

Almost surely, 2^21869631 is an apocalyptic number.

21869631 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21869631 is a deficient number, since it is larger than the sum of its proper divisors (15316713).

21869631 is a wasteful number, since it uses less digits than its factorization.

21869631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 612 (or 602 counting only the distinct ones).

The product of its digits is 15552, while the sum is 36.

The square root of 21869631 is about 4676.4977280012. The cubic root of 21869631 is about 279.6493527303.

It can be divided in two parts, 21869 and 631, that added together give a square (22500 = 150²).

The spelling of 21869631 in words is "twenty-one million, eight hundred sixty-nine thousand, six hundred thirty-one".