21523018 has 16 divisors (see below), whose sum is σ = 35312256. Its totient is φ = 9757440.

The previous prime is 21523001. The next prime is 21523049. The reversal of 21523018 is 81032512.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a self number, because there is not a number n which added to its sum of digits gives 21523018.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9130 + ... + 11242.

It is an arithmetic number, because the mean of its divisors is an integer number (2207016).

Almost surely, 2^21523018 is an apocalyptic number.

21523018 is a deficient number, since it is larger than the sum of its proper divisors (13789238).

21523018 is a wasteful number, since it uses less digits than its factorization.

21523018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2589.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21523018 is about 4639.2906785413. The cubic root of 21523018 is about 278.1640854551.

The spelling of 21523018 in words is "twenty-one million, five hundred twenty-three thousand, eighteen".