21645459 has 12 divisors (see below), whose sum is σ = 34108152. Its totient is φ = 13118400.

The previous prime is 21645451. The next prime is 21645473. The reversal of 21645459 is 95454612.

21645459 is a `hidden beast` number, since 2 + 1 + 645 + 4 + 5 + 9 = 666.

It is not a de Polignac number, because 21645459 - 2³ = 21645451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21645451) 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, 109222 + ... + 109419.

It is an arithmetic number, because the mean of its divisors is an integer number (2842346).

Almost surely, 2^21645459 is an apocalyptic number.

21645459 is a deficient number, since it is larger than the sum of its proper divisors (12462693).

21645459 is a wasteful number, since it uses less digits than its factorization.

21645459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218658 (or 218655 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 21645459 is about 4652.4680546996. The cubic root of 21645459 is about 278.6905653277.

It can be divided in two parts, 2 and 1645459, that added together give a palindrome (1645461).

The spelling of 21645459 in words is "twenty-one million, six hundred forty-five thousand, four hundred fifty-nine".