21690459 has 12 divisors (see below), whose sum is σ = 35806576. Its totient is φ = 12394512.

The previous prime is 21690451. The next prime is 21690467. The reversal of 21690459 is 95409612.

It is an interprime number because it is at equal distance from previous prime (21690451) and next prime (21690467).

It is not a de Polignac number, because 21690459 - 2³ = 21690451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21690451) 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, 172084 + ... + 172209.

Almost surely, 2^21690459 is an apocalyptic number.

21690459 is a deficient number, since it is larger than the sum of its proper divisors (14116117).

21690459 is a wasteful number, since it uses less digits than its factorization.

21690459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 344306 (or 344303 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The square root of 21690459 is about 4657.3016865992. The cubic root of 21690459 is about 278.8835603061.

The spelling of 21690459 in words is "twenty-one million, six hundred ninety thousand, four hundred fifty-nine".