21680438 has 16 divisors (see below), whose sum is σ = 35117376. Its totient is φ = 9979200.

The previous prime is 21680419. The next prime is 21680443. The reversal of 21680438 is 83408612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11138 + ... + 12938.

It is an arithmetic number, because the mean of its divisors is an integer number (2194836).

Almost surely, 2^21680438 is an apocalyptic number.

21680438 is a deficient number, since it is larger than the sum of its proper divisors (13436938).

21680438 is a wasteful number, since it uses less digits than its factorization.

21680438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2279.

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 21680438 is about 4656.2257247689. The cubic root of 21680438 is about 278.8406055881.

The spelling of 21680438 in words is "twenty-one million, six hundred eighty thousand, four hundred thirty-eight".