21234812 has 6 divisors (see below), whose sum is σ = 37160928. Its totient is φ = 10617404.

The previous prime is 21234809. The next prime is 21234817. The reversal of 21234812 is 21843212.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21234817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2654348 + ... + 2654355.

It is an arithmetic number, because the mean of its divisors is an integer number (6193488).

Almost surely, 2^21234812 is an apocalyptic number.

It is an amenable number.

21234812 is a deficient number, since it is larger than the sum of its proper divisors (15926116).

21234812 is a wasteful number, since it uses less digits than its factorization.

21234812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5308707 (or 5308705 counting only the distinct ones).

The product of its digits is 768, while the sum is 23.

The square root of 21234812 is about 4608.1245642886. The cubic root of 21234812 is about 276.9169078319.

Subtracting 21234812 from its reverse (21843212), we obtain a square (608400 = 780²).

The spelling of 21234812 in words is "twenty-one million, two hundred thirty-four thousand, eight hundred twelve".