21253172 has 24 divisors (see below), whose sum is σ = 40504800. Its totient is φ = 9719136.

The previous prime is 21253121. The next prime is 21253181. The reversal of 21253172 is 27135212.

It is a happy number.

It is a super-3 number, since 3×21253172³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2618 + ... + 7025.

It is an arithmetic number, because the mean of its divisors is an integer number (1687700).

Almost surely, 2^21253172 is an apocalyptic number.

It is an amenable number.

21253172 is a deficient number, since it is larger than the sum of its proper divisors (19251628).

21253172 is a wasteful number, since it uses less digits than its factorization.

21253172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9695 (or 9693 counting only the distinct ones).

The product of its digits is 840, while the sum is 23.

The square root of 21253172 is about 4610.1162675143. The cubic root of 21253172 is about 276.9966939528.

Adding to 21253172 its reverse (27135212), we get a palindrome (48388384).

The spelling of 21253172 in words is "twenty-one million, two hundred fifty-three thousand, one hundred seventy-two".