21642806 has 8 divisors (see below), whose sum is σ = 32490840. Its totient is φ = 10812528.

The previous prime is 21642799. The next prime is 21642833. The reversal of 21642806 is 60824612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21642806² = 936822103107272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 791 + ... + 6626.

It is an arithmetic number, because the mean of its divisors is an integer number (4061355).

Almost surely, 2^21642806 is an apocalyptic number.

21642806 is a deficient number, since it is larger than the sum of its proper divisors (10848034).

21642806 is a wasteful number, since it uses less digits than its factorization.

21642806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8878.

The product of its (nonzero) digits is 4608, while the sum is 29.

The square root of 21642806 is about 4652.1829284756. The cubic root of 21642806 is about 278.6791788551.

The spelling of 21642806 in words is "twenty-one million, six hundred forty-two thousand, eight hundred six".