21618678 has 16 divisors (see below), whose sum is σ = 43759296. Its totient is φ = 7119240.

The previous prime is 21618677. The next prime is 21618683. The reversal of 21618678 is 87681612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21618673) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21208 + ... + 22203.

It is an arithmetic number, because the mean of its divisors is an integer number (2734956).

Almost surely, 2^21618678 is an apocalyptic number.

21618678 is an abundant number, since it is smaller than the sum of its proper divisors (22140618).

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

21618678 is a wasteful number, since it uses less digits than its factorization.

21618678 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43499.

The product of its digits is 32256, while the sum is 39.

The square root of 21618678 is about 4649.5890140958. The cubic root of 21618678 is about 278.5755805899.

The spelling of 21618678 in words is "twenty-one million, six hundred eighteen thousand, six hundred seventy-eight".