21317172 has 24 divisors (see below), whose sum is σ = 50584800. Its totient is φ = 6985056.

The previous prime is 21317147. The next prime is 21317209. The reversal of 21317172 is 27171312.

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, 14347 + ... + 15762.

It is an arithmetic number, because the mean of its divisors is an integer number (2107700).

Almost surely, 2^21317172 is an apocalyptic number.

It is an amenable number.

21317172 is an abundant number, since it is smaller than the sum of its proper divisors (29267628).

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

21317172 is a wasteful number, since it uses less digits than its factorization.

21317172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30175 (or 30173 counting only the distinct ones).

The product of its digits is 588, while the sum is 24.

The square root of 21317172 is about 4617.0523063964. The cubic root of 21317172 is about 277.2744567807.

Adding to 21317172 its reverse (27171312), we get a palindrome (48488484).

The spelling of 21317172 in words is "twenty-one million, three hundred seventeen thousand, one hundred seventy-two".