21453165 has 12 divisors (see below), whose sum is σ = 37185564. Its totient is φ = 11441664.

The previous prime is 21453143. The next prime is 21453191. The reversal of 21453165 is 56135412.

It can be written as a sum of positive squares in 2 ways, for example, as 9715689 + 11737476 = 3117^2 + 3426^2 .

It is not a de Polignac number, because 21453165 - 2⁶ = 21453101 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 238324 + ... + 238413.

It is an arithmetic number, because the mean of its divisors is an integer number (3098797).

Almost surely, 2^21453165 is an apocalyptic number.

It is an amenable number.

21453165 is a deficient number, since it is larger than the sum of its proper divisors (15732399).

21453165 is a wasteful number, since it uses less digits than its factorization.

21453165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 476748 (or 476745 counting only the distinct ones).

The product of its digits is 3600, while the sum is 27.

The square root of 21453165 is about 4631.7561464309. The cubic root of 21453165 is about 277.8628319394.

Adding to 21453165 its reverse (56135412), we get a palindrome (77588577).

The spelling of 21453165 in words is "twenty-one million, four hundred fifty-three thousand, one hundred sixty-five".