21688612 has 24 divisors (see below), whose sum is σ = 41630400. Its totient is φ = 9804960.

The previous prime is 21688603. The next prime is 21688619.

21688612 is nontrivially palindromic in base 10.

It is not an unprimeable number, because it can be changed into a prime (21688619) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7518 + ... + 9994.

It is an arithmetic number, because the mean of its divisors is an integer number (1734600).

Almost surely, 2^21688612 is an apocalyptic number.

21688612 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21688612 is a deficient number, since it is larger than the sum of its proper divisors (19941788).

21688612 is a wasteful number, since it uses less digits than its factorization.

21688612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2691 (or 2689 counting only the distinct ones).

The product of its digits is 9216, while the sum is 34.

The square root of 21688612 is about 4657.1033915944. The cubic root of 21688612 is about 278.8756441903.

The spelling of 21688612 in words is "twenty-one million, six hundred eighty-eight thousand, six hundred twelve".