21689273 has 2 divisors, whose sum is σ = 21689274. Its totient is φ = 21689272.

The previous prime is 21689257. The next prime is 21689309. The reversal of 21689273 is 37298612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20866624 + 822649 = 4568^2 + 907^2 .

It is a cyclic number.

It is not a de Polignac number, because 21689273 - 2⁴ = 21689257 is a prime.

It is not a weakly prime, because it can be changed into another prime (21689233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10844636 + 10844637.

It is an arithmetic number, because the mean of its divisors is an integer number (10844637).

Almost surely, 2^21689273 is an apocalyptic number.

It is an amenable number.

21689273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21689273 is an equidigital number, since it uses as much as digits as its factorization.

21689273 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 38.

The square root of 21689273 is about 4657.1743579127. The cubic root of 21689273 is about 278.8784772428.

The spelling of 21689273 in words is "twenty-one million, six hundred eighty-nine thousand, two hundred seventy-three".