21406634 has 16 divisors (see below), whose sum is σ = 32915808. Its totient is φ = 10438032.

The previous prime is 21406589. The next prime is 21406643. The reversal of 21406634 is 43660412.

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, 13592 + ... + 15084.

It is an arithmetic number, because the mean of its divisors is an integer number (2057238).

Almost surely, 2^21406634 is an apocalyptic number.

21406634 is a deficient number, since it is larger than the sum of its proper divisors (11509174).

21406634 is a wasteful number, since it uses less digits than its factorization.

21406634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1669.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 21406634 is about 4626.7303790042. The cubic root of 21406634 is about 277.6617956452.

The spelling of 21406634 in words is "twenty-one million, four hundred six thousand, six hundred thirty-four".