21137812 has 12 divisors (see below), whose sum is σ = 37618560. Its totient is φ = 10389656.

The previous prime is 21137801. The next prime is 21137813. The reversal of 21137812 is 21873112.

It is a happy number.

It is a super-3 number, since 3×21137812³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21137813) 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, 44548 + ... + 45019.

It is an arithmetic number, because the mean of its divisors is an integer number (3134880).

Almost surely, 2^21137812 is an apocalyptic number.

It is an amenable number.

21137812 is a deficient number, since it is larger than the sum of its proper divisors (16480748).

21137812 is a wasteful number, since it uses less digits than its factorization.

21137812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89630 (or 89628 counting only the distinct ones).

The product of its digits is 672, while the sum is 25.

The square root of 21137812 is about 4597.5876283112. The cubic root of 21137812 is about 276.4946147255.

The spelling of 21137812 in words is "twenty-one million, one hundred thirty-seven thousand, eight hundred twelve".