21339806 has 16 divisors (see below), whose sum is σ = 32535216. Its totient is φ = 10496256.

The previous prime is 21339781. The next prime is 21339809. The reversal of 21339806 is 60893312.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21339809) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61325 + ... + 61671.

It is an arithmetic number, because the mean of its divisors is an integer number (2033451).

Almost surely, 2^21339806 is an apocalyptic number.

21339806 is a deficient number, since it is larger than the sum of its proper divisors (11195410).

21339806 is a wasteful number, since it uses less digits than its factorization.

21339806 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 763.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 21339806 is about 4619.5027870973. The cubic root of 21339806 is about 277.3725562565.

The spelling of 21339806 in words is "twenty-one million, three hundred thirty-nine thousand, eight hundred six".