21375651779 has 2 divisors, whose sum is σ = 21375651780. Its totient is φ = 21375651778.

The previous prime is 21375651769. The next prime is 21375651821. The reversal of 21375651779 is 97715657312.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21375651779 - 2²⁰ = 21374603203 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21375651779.

It is not a weakly prime, because it can be changed into another prime (21375651769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10687825889 + 10687825890.

It is an arithmetic number, because the mean of its divisors is an integer number (10687825890).

Almost surely, 2^21375651779 is an apocalyptic number.

21375651779 is a deficient number, since it is larger than the sum of its proper divisors (1).

21375651779 is an equidigital number, since it uses as much as digits as its factorization.

21375651779 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2778300, while the sum is 53.

The spelling of 21375651779 in words is "twenty-one billion, three hundred seventy-five million, six hundred fifty-one thousand, seven hundred seventy-nine".