21523023 has 24 divisors (see below), whose sum is σ = 32577200. Its totient is φ = 14043888.

The previous prime is 21523001. The next prime is 21523049. The reversal of 21523023 is 32032512.

It is not a de Polignac number, because 21523023 - 2⁹ = 21522511 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21522987 and 21523005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21523063) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 93873 + ... + 94101.

Almost surely, 2^21523023 is an apocalyptic number.

21523023 is a deficient number, since it is larger than the sum of its proper divisors (11054177).

21523023 is an equidigital number, since it uses as much as digits as its factorization.

21523023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 356 (or 291 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 18.

The square root of 21523023 is about 4639.2912174167. The cubic root of 21523023 is about 278.1641069951.

Adding to 21523023 its reverse (32032512), we get a palindrome (53555535).

The spelling of 21523023 in words is "twenty-one million, five hundred twenty-three thousand, twenty-three".