21288513 has 8 divisors (see below), whose sum is σ = 28808608. Its totient is φ = 13980384.

The previous prime is 21288503. The next prime is 21288517. The reversal of 21288513 is 31588212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21288513 - 2⁵ = 21288481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21288517) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52756 + ... + 53157.

It is an arithmetic number, because the mean of its divisors is an integer number (3601076).

Almost surely, 2^21288513 is an apocalyptic number.

It is an amenable number.

21288513 is a deficient number, since it is larger than the sum of its proper divisors (7520095).

21288513 is a wasteful number, since it uses less digits than its factorization.

21288513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105983.

The product of its digits is 3840, while the sum is 30.

The square root of 21288513 is about 4613.9476590009. The cubic root of 21288513 is about 277.1501442876.

The spelling of 21288513 in words is "twenty-one million, two hundred eighty-eight thousand, five hundred thirteen".