21682978879 has 4 divisors (see below), whose sum is σ = 21773702880. Its totient is φ = 21592254880.

The previous prime is 21682978841. The next prime is 21682978921. The reversal of 21682978879 is 97887928612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21682978879 - 2²¹ = 21680881727 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21682978829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45361642 + ... + 45362119.

It is an arithmetic number, because the mean of its divisors is an integer number (5443425720).

Almost surely, 2^21682978879 is an apocalyptic number.

21682978879 is a deficient number, since it is larger than the sum of its proper divisors (90724001).

21682978879 is an equidigital number, since it uses as much as digits as its factorization.

21682978879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90724000.

The product of its digits is 48771072, while the sum is 67.

The spelling of 21682978879 in words is "twenty-one billion, six hundred eighty-two million, nine hundred seventy-eight thousand, eight hundred seventy-nine".