21973812 has 24 divisors (see below), whose sum is σ = 58597056. Its totient is φ = 6278208.

The previous prime is 21973807. The next prime is 21973813. The reversal of 21973812 is 21837912.

It is a super-2 number, since 2×21973812² = 965696827622688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 130713 + ... + 130880.

It is an arithmetic number, because the mean of its divisors is an integer number (2441544).

Almost surely, 2^21973812 is an apocalyptic number.

It is an amenable number.

21973812 is an abundant number, since it is smaller than the sum of its proper divisors (36623244).

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

21973812 is a wasteful number, since it uses less digits than its factorization.

21973812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261607 (or 261605 counting only the distinct ones).

The product of its digits is 6048, while the sum is 33.

The square root of 21973812 is about 4687.6232783789. The cubic root of 21973812 is about 280.0927073966.

The spelling of 21973812 in words is "twenty-one million, nine hundred seventy-three thousand, eight hundred twelve".