21926821 has 8 divisors (see below), whose sum is σ = 26533440. Its totient is φ = 17688768.

The previous prime is 21926809. The next prime is 21926831. The reversal of 21926821 is 12862912.

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

It is a cyclic number.

It is not a de Polignac number, because 21926821 - 2¹⁵ = 21894053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21926831) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 92011 + ... + 92248.

It is an arithmetic number, because the mean of its divisors is an integer number (3316680).

Almost surely, 2^21926821 is an apocalyptic number.

It is an amenable number.

21926821 is a deficient number, since it is larger than the sum of its proper divisors (4606619).

21926821 is a wasteful number, since it uses less digits than its factorization.

21926821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184283.

The product of its digits is 3456, while the sum is 31.

The square root of 21926821 is about 4682.6083543256. The cubic root of 21926821 is about 279.8929054722.

The spelling of 21926821 in words is "twenty-one million, nine hundred twenty-six thousand, eight hundred twenty-one".