21144208979 has 2 divisors, whose sum is σ = 21144208980. Its totient is φ = 21144208978.

The previous prime is 21144208973. The next prime is 21144209039. The reversal of 21144208979 is 97980244112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21144208979 - 2¹² = 21144204883 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21144208973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10572104489 + 10572104490.

It is an arithmetic number, because the mean of its divisors is an integer number (10572104490).

Almost surely, 2^21144208979 is an apocalyptic number.

21144208979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21144208979 is an equidigital number, since it uses as much as digits as its factorization.

21144208979 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 290304, while the sum is 47.

The spelling of 21144208979 in words is "twenty-one billion, one hundred forty-four million, two hundred eight thousand, nine hundred seventy-nine".