21789618 has 16 divisors (see below), whose sum is σ = 45873120. Its totient is φ = 6880896.

The previous prime is 21789617. The next prime is 21789619. The reversal of 21789618 is 81698712.

It is an interprime number because it is at equal distance from previous prime (21789617) and next prime (21789619).

It is a self number, because there is not a number n which added to its sum of digits gives 21789618.

It is not an unprimeable number, because it can be changed into a prime (21789613) 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, 95455 + ... + 95682.

It is an arithmetic number, because the mean of its divisors is an integer number (2867070).

Almost surely, 2^21789618 is an apocalyptic number.

21789618 is an abundant number, since it is smaller than the sum of its proper divisors (24083502).

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

21789618 is a wasteful number, since it uses less digits than its factorization.

21789618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 191161.

The product of its digits is 48384, while the sum is 42.

The square root of 21789618 is about 4667.9350895230. The cubic root of 21789618 is about 279.3078909822.

The spelling of 21789618 in words is "twenty-one million, seven hundred eighty-nine thousand, six hundred eighteen".