21044099789 has 2 divisors, whose sum is σ = 21044099790. Its totient is φ = 21044099788.

The previous prime is 21044099759. The next prime is 21044099809. The reversal of 21044099789 is 98799044012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20633024164 + 411075625 = 143642^2 + 20275^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044099789 - 2⁸ = 21044099533 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21044099789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21044099729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522049894 + 10522049895.

It is an arithmetic number, because the mean of its divisors is an integer number (10522049895).

Almost surely, 2^21044099789 is an apocalyptic number.

It is an amenable number.

21044099789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21044099789 is an equidigital number, since it uses as much as digits as its factorization.

21044099789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1306368, while the sum is 53.

The spelling of 21044099789 in words is "twenty-one billion, forty-four million, ninety-nine thousand, seven hundred eighty-nine".