21518268 has 24 divisors (see below), whose sum is σ = 50467200. Its totient is φ = 7135920.

The previous prime is 21518267. The next prime is 21518269. The reversal of 21518268 is 86281512.

It is an interprime number because it is at equal distance from previous prime (21518267) and next prime (21518269).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2118 + ... + 6893.

It is an arithmetic number, because the mean of its divisors is an integer number (2102800).

Almost surely, 2^21518268 is an apocalyptic number.

It is an amenable number.

21518268 is an abundant number, since it is smaller than the sum of its proper divisors (28948932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21518268 is a wasteful number, since it uses less digits than its factorization.

21518268 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9217 (or 9215 counting only the distinct ones).

The product of its digits is 7680, while the sum is 33.

The square root of 21518268 is about 4638.7787185853. The cubic root of 21518268 is about 278.1436209054.

The spelling of 21518268 in words is "twenty-one million, five hundred eighteen thousand, two hundred sixty-eight".