21539212 has 12 divisors (see below), whose sum is σ = 37829736. Its totient is φ = 10730720.

The previous prime is 21539209. The next prime is 21539213. The reversal of 21539212 is 21293512.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21539213) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8458 + ... + 10705.

It is an arithmetic number, because the mean of its divisors is an integer number (3152478).

Almost surely, 2^21539212 is an apocalyptic number.

It is an amenable number.

21539212 is a deficient number, since it is larger than the sum of its proper divisors (16290524).

21539212 is a wasteful number, since it uses less digits than its factorization.

21539212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19448 (or 19446 counting only the distinct ones).

The product of its digits is 1080, while the sum is 25.

The square root of 21539212 is about 4641.0356602810. The cubic root of 21539212 is about 278.2338318682.

The spelling of 21539212 in words is "twenty-one million, five hundred thirty-nine thousand, two hundred twelve".