21425399207789 has 2 divisors, whose sum is σ = 21425399207790. Its totient is φ = 21425399207788.

The previous prime is 21425399207767. The next prime is 21425399207801. The reversal of 21425399207789 is 98770299352412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17545484145289 + 3879915062500 = 4188733^2 + 1969750^2 .

It is a cyclic number.

It is not a de Polignac number, because 21425399207789 - 2⁸ = 21425399207533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21422399207789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10712699603894 + 10712699603895.

It is an arithmetic number, because the mean of its divisors is an integer number (10712699603895).

Almost surely, 2^{21425399207789} is an apocalyptic number.

It is an amenable number.

21425399207789 is a deficient number, since it is larger than the sum of its proper divisors (1).

21425399207789 is an equidigital number, since it uses as much as digits as its factorization.

21425399207789 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 137168640, while the sum is 68.

The spelling of 21425399207789 in words is "twenty-one trillion, four hundred twenty-five billion, three hundred ninety-nine million, two hundred seven thousand, seven hundred eighty-nine".