21631023 has 16 divisors (see below), whose sum is σ = 32125440. Its totient is φ = 14384952.

The previous prime is 21631007. The next prime is 21631033. The reversal of 21631023 is 32013612.

It is not a de Polignac number, because 21631023 - 2⁴ = 21631007 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21630987 and 21631005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21631003) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14490 + ... + 15912.

It is an arithmetic number, because the mean of its divisors is an integer number (2007840).

Almost surely, 2^21631023 is an apocalyptic number.

21631023 is a deficient number, since it is larger than the sum of its proper divisors (10494417).

21631023 is a wasteful number, since it uses less digits than its factorization.

21631023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1995 (or 1989 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 18.

The square root of 21631023 is about 4650.9163613206. The cubic root of 21631023 is about 278.6285958753.

Adding to 21631023 its reverse (32013612), we get a palindrome (53644635).

The spelling of 21631023 in words is "twenty-one million, six hundred thirty-one thousand, twenty-three".