21689253 has 12 divisors (see below), whose sum is σ = 32691360. Its totient is φ = 13830696.

The previous prime is 21689237. The next prime is 21689257. The reversal of 21689253 is 35298612.

It is not a de Polignac number, because 21689253 - 2⁴ = 21689237 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21689257) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52183 + ... + 52596.

It is an arithmetic number, because the mean of its divisors is an integer number (2724280).

Almost surely, 2^21689253 is an apocalyptic number.

21689253 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21689253 is a deficient number, since it is larger than the sum of its proper divisors (11002107).

21689253 is a wasteful number, since it uses less digits than its factorization.

21689253 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104808 (or 104805 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 21689253 is about 4657.1722106875. The cubic root of 21689253 is about 278.8783915234.

The spelling of 21689253 in words is "twenty-one million, six hundred eighty-nine thousand, two hundred fifty-three".