21223931 has 8 divisors (see below), whose sum is σ = 22817280. Its totient is φ = 19678248.

The previous prime is 21223927. The next prime is 21223957. The reversal of 21223931 is 13932212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21223931 - 2² = 21223927 is a prime.

It is a super-2 number, since 2×21223931² = 900910494185522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21223897 and 21223906.

It is not an unprimeable number, because it can be changed into a prime (21223901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10991 + ... + 12776.

It is an arithmetic number, because the mean of its divisors is an integer number (2852160).

Almost surely, 2^21223931 is an apocalyptic number.

21223931 is a deficient number, since it is larger than the sum of its proper divisors (1593349).

21223931 is a wasteful number, since it uses less digits than its factorization.

21223931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23833.

The product of its digits is 648, while the sum is 23.

The square root of 21223931 is about 4606.9437808595. The cubic root of 21223931 is about 276.8696011156.

The spelling of 21223931 in words is "twenty-one million, two hundred twenty-three thousand, nine hundred thirty-one".