21572571 has 4 divisors (see below), whose sum is σ = 28763432. Its totient is φ = 14381712.

The previous prime is 21572567. The next prime is 21572587. The reversal of 21572571 is 17527512.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21572571 - 2² = 21572567 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21572501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3595426 + ... + 3595431.

It is an arithmetic number, because the mean of its divisors is an integer number (7190858).

Almost surely, 2^21572571 is an apocalyptic number.

21572571 is a deficient number, since it is larger than the sum of its proper divisors (7190861).

21572571 is an equidigital number, since it uses as much as digits as its factorization.

21572571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7190860.

The product of its digits is 4900, while the sum is 30.

The square root of 21572571 is about 4644.6281874871. The cubic root of 21572571 is about 278.3773966199.

The spelling of 21572571 in words is "twenty-one million, five hundred seventy-two thousand, five hundred seventy-one".