21718272 has 36 divisors (see below), whose sum is σ = 57804320. Its totient is φ = 7239168.

The previous prime is 21718267. The next prime is 21718327. The reversal of 21718272 is 27281712.

It is a happy number.

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, 13372 + ... + 14907.

Almost surely, 2^21718272 is an apocalyptic number.

It is an amenable number.

21718272 is an abundant number, since it is smaller than the sum of its proper divisors (36086048).

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

21718272 is an equidigital number, since it uses as much as digits as its factorization.

21718272 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28298 (or 28284 counting only the distinct ones).

The product of its digits is 3136, while the sum is 30.

The square root of 21718272 is about 4660.2866864604. The cubic root of 21718272 is about 279.0027106274.

Adding to 21718272 its reverse (27281712), we get a palindrome (48999984).

The spelling of 21718272 in words is "twenty-one million, seven hundred eighteen thousand, two hundred seventy-two".