21407806 has 12 divisors (see below), whose sum is σ = 37354608. Its totient is φ = 9174732.

The previous prime is 21407801. The next prime is 21407809. The reversal of 21407806 is 60870412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21407801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109126 + ... + 109321.

It is an arithmetic number, because the mean of its divisors is an integer number (3112884).

Almost surely, 2^21407806 is an apocalyptic number.

21407806 is a deficient number, since it is larger than the sum of its proper divisors (15946802).

21407806 is a wasteful number, since it uses less digits than its factorization.

21407806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218463 (or 218456 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 28.

The square root of 21407806 is about 4626.8570325870. The cubic root of 21407806 is about 277.6668628234. Note that the first 3 decimals are identical.

The spelling of 21407806 in words is "twenty-one million, four hundred seven thousand, eight hundred six".