21401908 has 12 divisors (see below), whose sum is σ = 40858272. Its totient is φ = 9728120.

The previous prime is 21401903. The next prime is 21401927. The reversal of 21401908 is 80910412.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21401903) 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, 243160 + ... + 243247.

It is an arithmetic number, because the mean of its divisors is an integer number (3404856).

Almost surely, 2^21401908 is an apocalyptic number.

It is an amenable number.

21401908 is a deficient number, since it is larger than the sum of its proper divisors (19456364).

21401908 is a wasteful number, since it uses less digits than its factorization.

21401908 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486422 (or 486420 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 21401908 is about 4626.2196229751. The cubic root of 21401908 is about 277.6413607616.

The spelling of 21401908 in words is "twenty-one million, four hundred one thousand, nine hundred eight".