21897212 has 6 divisors (see below), whose sum is σ = 38320128. Its totient is φ = 10948604.

The previous prime is 21897193. The next prime is 21897223. The reversal of 21897212 is 21279812.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2737148 + ... + 2737155.

It is an arithmetic number, because the mean of its divisors is an integer number (6386688).

Almost surely, 2^21897212 is an apocalyptic number.

It is an amenable number.

21897212 is a deficient number, since it is larger than the sum of its proper divisors (16422916).

21897212 is a wasteful number, since it uses less digits than its factorization.

21897212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5474307 (or 5474305 counting only the distinct ones).

The product of its digits is 4032, while the sum is 32.

The square root of 21897212 is about 4679.4456936693. The cubic root of 21897212 is about 279.7668637609.

The spelling of 21897212 in words is "twenty-one million, eight hundred ninety-seven thousand, two hundred twelve".