21227172 has 24 divisors (see below), whose sum is σ = 49730016. Its totient is φ = 7047168.

The previous prime is 21227113. The next prime is 21227177. The reversal of 21227172 is 27172212.

It is a super-2 number, since 2×21227172² = 901185662235168, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21227177) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 358 + ... + 6525.

It is an arithmetic number, because the mean of its divisors is an integer number (2072084).

Almost surely, 2^21227172 is an apocalyptic number.

It is an amenable number.

21227172 is an abundant number, since it is smaller than the sum of its proper divisors (28502844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21227172 is a wasteful number, since it uses less digits than its factorization.

21227172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7147 (or 7145 counting only the distinct ones).

The product of its digits is 784, while the sum is 24.

The square root of 21227172 is about 4607.2955190654. The cubic root of 21227172 is about 276.8836935208.

Adding to 21227172 its reverse (27172212), we get a palindrome (48399384).

The spelling of 21227172 in words is "twenty-one million, two hundred twenty-seven thousand, one hundred seventy-two".