21679389 has 12 divisors (see below), whose sum is σ = 31593276. Its totient is φ = 14324352.

The previous prime is 21679379. The next prime is 21679393. The reversal of 21679389 is 98397612.

It can be written as a sum of positive squares in 2 ways, for example, as 12131289 + 9548100 = 3483^2 + 3090^2 .

It is not a de Polignac number, because 21679389 - 2¹³ = 21671197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21679309) 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 11 ways as a sum of consecutive naturals, for example, 9642 + ... + 11675.

It is an arithmetic number, because the mean of its divisors is an integer number (2632773).

Almost surely, 2^21679389 is an apocalyptic number.

It is an amenable number.

21679389 is a deficient number, since it is larger than the sum of its proper divisors (9913887).

21679389 is a wasteful number, since it uses less digits than its factorization.

21679389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21436 (or 21433 counting only the distinct ones).

The product of its digits is 163296, while the sum is 45.

The square root of 21679389 is about 4656.1130785238. The cubic root of 21679389 is about 278.8361083156.

The spelling of 21679389 in words is "twenty-one million, six hundred seventy-nine thousand, three hundred eighty-nine".