21249172 has 12 divisors (see below), whose sum is σ = 42498400. Its totient is φ = 9106776.

The previous prime is 21249161. The next prime is 21249191. The reversal of 21249172 is 27194212.

21249172 is an admirable number.

It is a Harshad number since it is a multiple of its sum of digits (28), and also a Moran number because the ratio is a prime number: 758899 = 21249172 / (2 + 1 + 2 + 4 + 9 + 1 + 7 + 2).

It is a self number, because there is not a number n which added to its sum of digits gives 21249172.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 379422 + ... + 379477.

Almost surely, 2^21249172 is an apocalyptic number.

It is an amenable number.

21249172 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21249172 is a wasteful number, since it uses less digits than its factorization.

21249172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 758910 (or 758908 counting only the distinct ones).

The product of its digits is 2016, while the sum is 28.

The square root of 21249172 is about 4609.6824185620. The cubic root of 21249172 is about 276.9793152718.

The spelling of 21249172 in words is "twenty-one million, two hundred forty-nine thousand, one hundred seventy-two".