21497172 has 12 divisors (see below), whose sum is σ = 50160096. Its totient is φ = 7165720.

The previous prime is 21497141. The next prime is 21497183. The reversal of 21497172 is 27179412.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

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, 895704 + ... + 895727.

It is an arithmetic number, because the mean of its divisors is an integer number (4180008).

Almost surely, 2^21497172 is an apocalyptic number.

It is an amenable number.

21497172 is an abundant number, since it is smaller than the sum of its proper divisors (28662924).

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

21497172 is a wasteful number, since it uses less digits than its factorization.

21497172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1791438 (or 1791436 counting only the distinct ones).

The product of its digits is 7056, while the sum is 33.

The square root of 21497172 is about 4636.5042866366. The cubic root of 21497172 is about 278.0526960472.

The spelling of 21497172 in words is "twenty-one million, four hundred ninety-seven thousand, one hundred seventy-two".