21845564 has 48 divisors (see below), whose sum is σ = 42872256. Its totient is φ = 9676800.

The previous prime is 21845563. The next prime is 21845597. The reversal of 21845564 is 46554812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21845563) 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 15 ways as a sum of consecutive naturals, for example, 225164 + ... + 225260.

It is an arithmetic number, because the mean of its divisors is an integer number (893172).

Almost surely, 2^21845564 is an apocalyptic number.

It is an amenable number.

21845564 is a deficient number, since it is larger than the sum of its proper divisors (21026692).

21845564 is a wasteful number, since it uses less digits than its factorization.

21845564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 244 counting only the distinct ones).

The product of its digits is 38400, while the sum is 35.

The square root of 21845564 is about 4673.9238333546. The cubic root of 21845564 is about 279.5467326276.

The spelling of 21845564 in words is "twenty-one million, eight hundred forty-five thousand, five hundred sixty-four".