21223538 has 16 divisors (see below), whose sum is σ = 36578304. Its totient is φ = 9047040.

The previous prime is 21223519. The next prime is 21223583. The reversal of 21223538 is 83532212.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1295 + ... + 6642.

It is an arithmetic number, because the mean of its divisors is an integer number (2286144).

Almost surely, 2^21223538 is an apocalyptic number.

21223538 is a deficient number, since it is larger than the sum of its proper divisors (15354766).

21223538 is a wasteful number, since it uses less digits than its factorization.

21223538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8137.

The product of its digits is 2880, while the sum is 26.

The square root of 21223538 is about 4606.9011276562. The cubic root of 21223538 is about 276.8678921890.

The spelling of 21223538 in words is "twenty-one million, two hundred twenty-three thousand, five hundred thirty-eight".