21513345 has 32 divisors (see below), whose sum is σ = 39521280. Its totient is φ = 9789120.

The previous prime is 21513329. The next prime is 21513361. The reversal of 21513345 is 54331512.

It is an interprime number because it is at equal distance from previous prime (21513329) and next prime (21513361).

It is not a de Polignac number, because 21513345 - 2⁴ = 21513329 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 34446 + ... + 35064.

It is an arithmetic number, because the mean of its divisors is an integer number (1235040).

Almost surely, 2^21513345 is an apocalyptic number.

It is an amenable number.

21513345 is a deficient number, since it is larger than the sum of its proper divisors (18007935).

21513345 is a wasteful number, since it uses less digits than its factorization.

21513345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 965.

The product of its digits is 1800, while the sum is 24.

The square root of 21513345 is about 4638.2480528751. The cubic root of 21513345 is about 278.1224078368.

Adding to 21513345 its reverse (54331512), we get a palindrome (75844857).

The spelling of 21513345 in words is "twenty-one million, five hundred thirteen thousand, three hundred forty-five".