21955571 has 12 divisors (see below), whose sum is σ = 24246432. Its totient is φ = 19866000.

The previous prime is 21955567. The next prime is 21955573. The reversal of 21955571 is 17555912.

It is not a de Polignac number, because 21955571 - 2² = 21955567 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21955573) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50726 + ... + 51156.

It is an arithmetic number, because the mean of its divisors is an integer number (2020536).

Almost surely, 2^21955571 is an apocalyptic number.

21955571 is a deficient number, since it is larger than the sum of its proper divisors (2290861).

21955571 is a wasteful number, since it uses less digits than its factorization.

21955571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 874 (or 863 counting only the distinct ones).

The product of its digits is 15750, while the sum is 35.

The square root of 21955571 is about 4685.6772189300. The cubic root of 21955571 is about 280.0151819999.

The spelling of 21955571 in words is "twenty-one million, nine hundred fifty-five thousand, five hundred seventy-one".