21219999979 has 2 divisors, whose sum is σ = 21219999980. Its totient is φ = 21219999978.

The previous prime is 21219999949. The next prime is 21220000001. The reversal of 21219999979 is 97999991212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21219999979 - 2²⁵ = 21186445547 is a prime.

It is not a weakly prime, because it can be changed into another prime (21219999929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10609999989 + 10609999990.

It is an arithmetic number, because the mean of its divisors is an integer number (10609999990).

Almost surely, 2^21219999979 is an apocalyptic number.

21219999979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21219999979 is an equidigital number, since it uses as much as digits as its factorization.

21219999979 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14880348, while the sum is 67.

The spelling of 21219999979 in words is "twenty-one billion, two hundred nineteen million, nine hundred ninety-nine thousand, nine hundred seventy-nine".