21723631 has 8 divisors (see below), whose sum is σ = 22956800. Its totient is φ = 20499480.

The previous prime is 21723589. The next prime is 21723641. The reversal of 21723631 is 13632712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21723631 - 2²¹ = 19626479 is a prime.

It is a super-2 number, since 2×21723631² = 943832287648322, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21723596 and 21723605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21723641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3040 + ... + 7258.

It is an arithmetic number, because the mean of its divisors is an integer number (2869600).

Almost surely, 2^21723631 is an apocalyptic number.

21723631 is a deficient number, since it is larger than the sum of its proper divisors (1233169).

21723631 is a wasteful number, since it uses less digits than its factorization.

21723631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4509.

The product of its digits is 1512, while the sum is 25.

The square root of 21723631 is about 4660.8616156243. The cubic root of 21723631 is about 279.0256567833.

The spelling of 21723631 in words is "twenty-one million, seven hundred twenty-three thousand, six hundred thirty-one".