21675412878 has 16 divisors (see below), whose sum is σ = 49543800960. Its totient is φ = 6192975096.

The previous prime is 21675412849. The next prime is 21675412883. The reversal of 21675412878 is 87821457612.

It is a happy number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21675412878.

It is a congruent number.

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, 258040588 + ... + 258040671.

It is an arithmetic number, because the mean of its divisors is an integer number (3096487560).

Almost surely, 2^21675412878 is an apocalyptic number.

21675412878 is an abundant number, since it is smaller than the sum of its proper divisors (27868388082).

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

21675412878 is a wasteful number, since it uses less digits than its factorization.

21675412878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 516081271.

The product of its digits is 1505280, while the sum is 51.

The spelling of 21675412878 in words is "twenty-one billion, six hundred seventy-five million, four hundred twelve thousand, eight hundred seventy-eight".