21537227 has 4 divisors (see below), whose sum is σ = 22279920. Its totient is φ = 20794536.

The previous prime is 21537179. The next prime is 21537251. The reversal of 21537227 is 72273512.

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

It is a cyclic number.

It is not a de Polignac number, because 21537227 - 2⁶ = 21537163 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 742663 = 21537227 / (2 + 1 + 5 + 3 + 7 + 2 + 2 + 7).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21537227.

It is not an unprimeable number, because it can be changed into a prime (21537427) by changing a digit.

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, 371303 + ... + 371360.

It is an arithmetic number, because the mean of its divisors is an integer number (5569980).

Almost surely, 2^21537227 is an apocalyptic number.

21537227 is a deficient number, since it is larger than the sum of its proper divisors (742693).

21537227 is an equidigital number, since it uses as much as digits as its factorization.

21537227 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 742692.

The product of its digits is 5880, while the sum is 29.

The square root of 21537227 is about 4640.8218022243. The cubic root of 21537227 is about 278.2252844939.

The spelling of 21537227 in words is "twenty-one million, five hundred thirty-seven thousand, two hundred twenty-seven".