21572091 has 24 divisors (see below), whose sum is σ = 32741280. Its totient is φ = 13686288.

The previous prime is 21572077. The next prime is 21572119. The reversal of 21572091 is 19027512.

21572091 is a `hidden beast` number, since 2 + 1 + 572 + 0 + 91 = 666.

It is not a de Polignac number, because 21572091 - 2⁵ = 21572059 is a prime.

It is a super-2 number, since 2×21572091² = 930710220224562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21572041) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 109405 + ... + 109601.

It is an arithmetic number, because the mean of its divisors is an integer number (1364220).

Almost surely, 2^21572091 is an apocalyptic number.

21572091 is a deficient number, since it is larger than the sum of its proper divisors (11169189).

21572091 is an equidigital number, since it uses as much as digits as its factorization.

21572091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21572091 is about 4644.5765146028. The cubic root of 21572091 is about 278.3753319280.

The spelling of 21572091 in words is "twenty-one million, five hundred seventy-two thousand, ninety-one".