21916390 has 16 divisors (see below), whose sum is σ = 39762432. Its totient is φ = 8697024.

The previous prime is 21916387. The next prime is 21916393. The reversal of 21916390 is 9361912.

It is an interprime number because it is at equal distance from previous prime (21916387) and next prime (21916393).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21916393) 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, 7359 + ... + 9898.

It is an arithmetic number, because the mean of its divisors is an integer number (2485152).

Almost surely, 2^21916390 is an apocalyptic number.

21916390 is a deficient number, since it is larger than the sum of its proper divisors (17846042).

21916390 is a wasteful number, since it uses less digits than its factorization.

21916390 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17391.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21916390 is about 4681.4944195203. The cubic root of 21916390 is about 279.8485149975.

The spelling of 21916390 in words is "twenty-one million, nine hundred sixteen thousand, three hundred ninety".