21973216 has 24 divisors (see below), whose sum is σ = 43711920. Its totient is φ = 10871808.

The previous prime is 21973207. The next prime is 21973223. The reversal of 21973216 is 61237912.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 436 + ... + 6643.

It is an arithmetic number, because the mean of its divisors is an integer number (1821330).

Almost surely, 2^21973216 is an apocalyptic number.

It is an amenable number.

21973216 is a deficient number, since it is larger than the sum of its proper divisors (21738704).

21973216 is an equidigital number, since it uses as much as digits as its factorization.

21973216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7186 (or 7178 counting only the distinct ones).

The product of its digits is 4536, while the sum is 31.

The square root of 21973216 is about 4687.5597062864. The cubic root of 21973216 is about 280.0901750373.

The spelling of 21973216 in words is "twenty-one million, nine hundred seventy-three thousand, two hundred sixteen".