21557822 has 16 divisors (see below), whose sum is σ = 37990512. Its totient is φ = 9045120.

The previous prime is 21557807. The next prime is 21557843. The reversal of 21557822 is 22875512.

It is a happy number.

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 7 ways as a sum of consecutive naturals, for example, 37403 + ... + 37974.

It is an arithmetic number, because the mean of its divisors is an integer number (2374407).

Almost surely, 2^21557822 is an apocalyptic number.

21557822 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21557822 is a deficient number, since it is larger than the sum of its proper divisors (16432690).

21557822 is a wasteful number, since it uses less digits than its factorization.

21557822 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75403.

The product of its digits is 11200, while the sum is 32.

The square root of 21557822 is about 4643.0401678211. The cubic root of 21557822 is about 278.3139406650.

The spelling of 21557822 in words is "twenty-one million, five hundred fifty-seven thousand, eight hundred twenty-two".