21973312 has 14 divisors (see below), whose sum is σ = 43603418. Its totient is φ = 10986624.

The previous prime is 21973309. The next prime is 21973319. The reversal of 21973312 is 21337912.

It can be written as a sum of positive squares in only one way, i.e., 21307456 + 665856 = 4616^2 + 816^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 171603 + ... + 171730.

Almost surely, 2^21973312 is an apocalyptic number.

It is an amenable number.

21973312 is a deficient number, since it is larger than the sum of its proper divisors (21630106).

21973312 is an equidigital number, since it uses as much as digits as its factorization.

21973312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343345 (or 343335 counting only the distinct ones).

The product of its digits is 2268, while the sum is 28.

The square root of 21973312 is about 4687.5699461448. The cubic root of 21973312 is about 280.0905829372.

The spelling of 21973312 in words is "twenty-one million, nine hundred seventy-three thousand, three hundred twelve".