21407816 has 16 divisors (see below), whose sum is σ = 40189500. Its totient is φ = 10690624.

The previous prime is 21407809. The next prime is 21407821. The reversal of 21407816 is 61870412.

It can be written as a sum of positive squares in 2 ways, for example, as 16434916 + 4972900 = 4054^2 + 2230^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10010 + ... + 11958.

Almost surely, 2^21407816 is an apocalyptic number.

It is an amenable number.

21407816 is a deficient number, since it is larger than the sum of its proper divisors (18781684).

21407816 is a wasteful number, since it uses less digits than its factorization.

21407816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3328 (or 3324 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21407816 is about 4626.8581132341. The cubic root of 21407816 is about 277.6669060579. Note that the first 3 decimals are identical.

The spelling of 21407816 in words is "twenty-one million, four hundred seven thousand, eight hundred sixteen".