21125212 has 24 divisors (see below), whose sum is σ = 38054016. Its totient is φ = 10255728.

The previous prime is 21125183. The next prime is 21125219. The reversal of 21125212 is 21252112.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125219) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45003 + ... + 45469.

It is an arithmetic number, because the mean of its divisors is an integer number (1585584).

Almost surely, 2^21125212 is an apocalyptic number.

It is an amenable number.

21125212 is a deficient number, since it is larger than the sum of its proper divisors (16928804).

21125212 is a wasteful number, since it uses less digits than its factorization.

21125212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 777 (or 775 counting only the distinct ones).

The product of its digits is 80, while the sum is 16.

The square root of 21125212 is about 4596.2171402143. The cubic root of 21125212 is about 276.4396654148.

Adding to 21125212 its reverse (21252112), we get a palindrome (42377324).

The spelling of 21125212 in words is "twenty-one million, one hundred twenty-five thousand, two hundred twelve".