21988023 has 16 divisors (see below), whose sum is σ = 30750720. Its totient is φ = 13948704.

The previous prime is 21988019. The next prime is 21988037. The reversal of 21988023 is 32088912.

It is not a de Polignac number, because 21988023 - 2² = 21988019 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21988823) 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, 14673 + ... + 16101.

It is an arithmetic number, because the mean of its divisors is an integer number (1921920).

Almost surely, 2^21988023 is an apocalyptic number.

21988023 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21988023 is a deficient number, since it is larger than the sum of its proper divisors (8762697).

21988023 is a wasteful number, since it uses less digits than its factorization.

21988023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1678.

The product of its (nonzero) digits is 6912, while the sum is 33.

The square root of 21988023 is about 4689.1388335173. The cubic root of 21988023 is about 280.1530753125.

The spelling of 21988023 in words is "twenty-one million, nine hundred eighty-eight thousand, twenty-three".