21423623 has 12 divisors (see below), whose sum is σ = 23431320. Its totient is φ = 19577376.

The previous prime is 21423613. The next prime is 21423631. The reversal of 21423623 is 32632412.

It is not a de Polignac number, because 21423623 - 2⁶ = 21423559 is a prime.

It is a super-2 number, since 2×21423623² = 917943244892258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423613) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17840 + ... + 19002.

It is an arithmetic number, because the mean of its divisors is an integer number (1952610).

Almost surely, 2^21423623 is an apocalyptic number.

21423623 is a deficient number, since it is larger than the sum of its proper divisors (2007697).

21423623 is a wasteful number, since it uses less digits than its factorization.

21423623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1298 (or 1285 counting only the distinct ones).

The product of its digits is 1728, while the sum is 23.

The square root of 21423623 is about 4628.5659766282. The cubic root of 21423623 is about 277.7352300284.

The spelling of 21423623 in words is "twenty-one million, four hundred twenty-three thousand, six hundred twenty-three".