21487923 has 20 divisors (see below), whose sum is σ = 32240208. Its totient is φ = 14262480.

The previous prime is 21487919. The next prime is 21487951. The reversal of 21487923 is 32978412.

It is not a de Polignac number, because 21487923 - 2² = 21487919 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21483923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 24765 + ... + 25617.

Almost surely, 2^21487923 is an apocalyptic number.

21487923 is a deficient number, since it is larger than the sum of its proper divisors (10752285).

21487923 is an equidigital number, since it uses as much as digits as its factorization.

21487923 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1176 (or 1167 counting only the distinct ones).

The product of its digits is 24192, while the sum is 36.

The square root of 21487923 is about 4635.5067684127. The cubic root of 21487923 is about 278.0128136184.

The spelling of 21487923 in words is "twenty-one million, four hundred eighty-seven thousand, nine hundred twenty-three".