21925821 has 8 divisors (see below), whose sum is σ = 29303680. Its totient is φ = 14582592.

The previous prime is 21925807. The next prime is 21925837. The reversal of 21925821 is 12852912.

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

It is not a de Polignac number, because 21925821 - 2⁵ = 21925789 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 (21925021) 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, 7141 + ... + 9738.

It is an arithmetic number, because the mean of its divisors is an integer number (3662960).

Almost surely, 2^21925821 is an apocalyptic number.

It is an amenable number.

21925821 is a deficient number, since it is larger than the sum of its proper divisors (7377859).

21925821 is a wasteful number, since it uses less digits than its factorization.

21925821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17315.

The product of its digits is 2880, while the sum is 30.

The square root of 21925821 is about 4682.5015750131. The cubic root of 21925821 is about 279.8886504526. Note that the first 3 decimals are identical.

The spelling of 21925821 in words is "twenty-one million, nine hundred twenty-five thousand, eight hundred twenty-one".