21678042 has 16 divisors (see below), whose sum is σ = 43475040. Its totient is φ = 7206192.

The previous prime is 21678037. The next prime is 21678049. The reversal of 21678042 is 24087612.

It is not an unprimeable number, because it can be changed into a prime (21678049) 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, 2493 + ... + 7040.

It is an arithmetic number, because the mean of its divisors is an integer number (2717190).

Almost surely, 2^21678042 is an apocalyptic number.

21678042 is an abundant number, since it is smaller than the sum of its proper divisors (21796998).

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

21678042 is a wasteful number, since it uses less digits than its factorization.

21678042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9917.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21678042 is about 4655.9684277280. The cubic root of 21678042 is about 278.8303332448.

The spelling of 21678042 in words is "twenty-one million, six hundred seventy-eight thousand, forty-two".