21453172 has 12 divisors (see below), whose sum is σ = 40431076. Its totient is φ = 9901440.

The previous prime is 21453143. The next prime is 21453191. The reversal of 21453172 is 27135412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 10929636 + 10523536 = 3306^2 + 3244^2 .

It is a super-3 number, since 3×21453172³ (a number of 23 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 206229 + ... + 206332.

Almost surely, 2^21453172 is an apocalyptic number.

It is an amenable number.

21453172 is a deficient number, since it is larger than the sum of its proper divisors (18977904).

21453172 is a wasteful number, since it uses less digits than its factorization.

21453172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 412578 (or 412576 counting only the distinct ones).

The product of its digits is 1680, while the sum is 25.

The square root of 21453172 is about 4631.7569020837. The cubic root of 21453172 is about 277.8628621609.

Adding to 21453172 its reverse (27135412), we get a palindrome (48588584).

The spelling of 21453172 in words is "twenty-one million, four hundred fifty-three thousand, one hundred seventy-two".