21897916 has 12 divisors (see below), whose sum is σ = 38752560. Its totient is φ = 10825760.

The previous prime is 21897913. The next prime is 21897949. The reversal of 21897916 is 61979812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21897913) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30400 + ... + 31111.

It is an arithmetic number, because the mean of its divisors is an integer number (3229380).

Almost surely, 2^21897916 is an apocalyptic number.

It is an amenable number.

21897916 is a deficient number, since it is larger than the sum of its proper divisors (16854644).

21897916 is a wasteful number, since it uses less digits than its factorization.

21897916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61604 (or 61602 counting only the distinct ones).

The product of its digits is 54432, while the sum is 43.

The square root of 21897916 is about 4679.5209156494. The cubic root of 21897916 is about 279.7698619167.

The spelling of 21897916 in words is "twenty-one million, eight hundred ninety-seven thousand, nine hundred sixteen".