21496638979 has 4 divisors (see below), whose sum is σ = 21499872880. Its totient is φ = 21493405080.

The previous prime is 21496638929. The next prime is 21496639013. The reversal of 21496638979 is 97983669412.

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 21496638979 - 2¹⁵ = 21496606211 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21496638979.

It is not an unprimeable number, because it can be changed into a prime (21496638929) 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, 1606959 + ... + 1620280.

It is an arithmetic number, because the mean of its divisors is an integer number (5374968220).

Almost surely, 2^21496638979 is an apocalyptic number.

21496638979 is a deficient number, since it is larger than the sum of its proper divisors (3233901).

21496638979 is an equidigital number, since it uses as much as digits as its factorization.

21496638979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3233900.

The product of its digits is 35271936, while the sum is 64.

The spelling of 21496638979 in words is "twenty-one billion, four hundred ninety-six million, six hundred thirty-eight thousand, nine hundred seventy-nine".