21689212 has 24 divisors (see below), whose sum is σ = 41489280. Its totient is φ = 9876480.

The previous prime is 21689197. The next prime is 21689233. The reversal of 21689212 is 21298612.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3037 + ... + 7252.

It is an arithmetic number, because the mean of its divisors is an integer number (1728720).

Almost surely, 2^21689212 is an apocalyptic number.

It is an amenable number.

21689212 is a deficient number, since it is larger than the sum of its proper divisors (19800068).

21689212 is a wasteful number, since it uses less digits than its factorization.

21689212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10341 (or 10339 counting only the distinct ones).

The product of its digits is 3456, while the sum is 31.

The square root of 21689212 is about 4657.1678088727. The cubic root of 21689212 is about 278.8782157986.

The spelling of 21689212 in words is "twenty-one million, six hundred eighty-nine thousand, two hundred twelve".