21489399 has 12 divisors (see below), whose sum is σ = 32674200. Its totient is φ = 13572144.

The previous prime is 21489389. The next prime is 21489401. The reversal of 21489399 is 99398412.

It is not a de Polignac number, because 21489399 - 2⁵ = 21489367 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21489329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 62664 + ... + 63005.

It is an arithmetic number, because the mean of its divisors is an integer number (2722850).

Almost surely, 2^21489399 is an apocalyptic number.

21489399 is a deficient number, since it is larger than the sum of its proper divisors (11184801).

21489399 is a wasteful number, since it uses less digits than its factorization.

21489399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125694 (or 125691 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21489399 is about 4635.6659715730. The cubic root of 21489399 is about 278.0191790160.

The spelling of 21489399 in words is "twenty-one million, four hundred eighty-nine thousand, three hundred ninety-nine".