21513545 has 16 divisors (see below), whose sum is σ = 26991360. Its totient is φ = 16445184.

The previous prime is 21513523. The next prime is 21513559. The reversal of 21513545 is 54531512.

It is a cyclic number.

It is not a de Polignac number, because 21513545 - 2¹⁸ = 21251401 is a prime.

It is a Curzon number.

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9041 + ... + 11169.

It is an arithmetic number, because the mean of its divisors is an integer number (1686960).

Almost surely, 2^21513545 is an apocalyptic number.

It is an amenable number.

21513545 is a deficient number, since it is larger than the sum of its proper divisors (5477815).

21513545 is a wasteful number, since it uses less digits than its factorization.

21513545 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2224.

The product of its digits is 3000, while the sum is 26.

The square root of 21513545 is about 4638.2696126896. The cubic root of 21513545 is about 278.1232696942.

The spelling of 21513545 in words is "twenty-one million, five hundred thirteen thousand, five hundred forty-five".