21915844 has 12 divisors (see below), whose sum is σ = 38414124. Its totient is φ = 10940384.

The previous prime is 21915833. The next prime is 21915857. The reversal of 21915844 is 44851912.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17556100 + 4359744 = 4190^2 + 2088^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1339 + ... + 6754.

It is an arithmetic number, because the mean of its divisors is an integer number (3201177).

Almost surely, 2^21915844 is an apocalyptic number.

It is an amenable number.

21915844 is a deficient number, since it is larger than the sum of its proper divisors (16498280).

21915844 is a wasteful number, since it uses less digits than its factorization.

21915844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8774 (or 8772 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 21915844 is about 4681.4361044449. The cubic root of 21915844 is about 279.8461910357.

The spelling of 21915844 in words is "twenty-one million, nine hundred fifteen thousand, eight hundred forty-four".