21427172 has 36 divisors (see below), whose sum is σ = 42042420. Its totient is φ = 9539712.

The previous prime is 21427171. The next prime is 21427183. The reversal of 21427172 is 27172412.

It can be written as a sum of positive squares in 6 ways, for example, as 45796 + 21381376 = 214^2 + 4624^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is not an unprimeable number, because it can be changed into a prime (21427171) 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, 19058 + ... + 20150.

It is an arithmetic number, because the mean of its divisors is an integer number (1167845).

Almost surely, 2^21427172 is an apocalyptic number.

It is an amenable number.

21427172 is a deficient number, since it is larger than the sum of its proper divisors (20615248).

21427172 is a wasteful number, since it uses less digits than its factorization.

21427172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1152 (or 1137 counting only the distinct ones).

The product of its digits is 1568, while the sum is 26.

The square root of 21427172 is about 4628.9493408332. The cubic root of 21427172 is about 277.7505655595.

Adding to 21427172 its reverse (27172412), we get a palindrome (48599584).

The spelling of 21427172 in words is "twenty-one million, four hundred twenty-seven thousand, one hundred seventy-two".