21908138 has 16 divisors (see below), whose sum is σ = 39766464. Its totient is φ = 8836800.

The previous prime is 21908119. The next prime is 21908141. The reversal of 21908138 is 83180912.

It is a Curzon 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, 45788 + ... + 46263.

It is an arithmetic number, because the mean of its divisors is an integer number (2485404).

Almost surely, 2^21908138 is an apocalyptic number.

21908138 is a deficient number, since it is larger than the sum of its proper divisors (17858326).

21908138 is a wasteful number, since it uses less digits than its factorization.

21908138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92077.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 21908138 is about 4680.6129940426. The cubic root of 21908138 is about 279.8133875602.

The spelling of 21908138 in words is "twenty-one million, nine hundred eight thousand, one hundred thirty-eight".