21395779587829 has 2 divisors, whose sum is σ = 21395779587830. Its totient is φ = 21395779587828.

The previous prime is 21395779587781. The next prime is 21395779587877. The reversal of 21395779587829 is 92878597759312.

It is a balanced prime because it is at equal distance from previous prime (21395779587781) and next prime (21395779587877).

It can be written as a sum of positive squares in only one way, i.e., 14319791222500 + 7075988365329 = 3784150^2 + 2660073^2 .

It is a cyclic number.

It is not a de Polignac number, because 21395779587829 - 2¹⁷ = 21395779456757 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21395779587529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697889793914 + 10697889793915.

It is an arithmetic number, because the mean of its divisors is an integer number (10697889793915).

Almost surely, 2^{21395779587829} is an apocalyptic number.

It is an amenable number.

21395779587829 is a deficient number, since it is larger than the sum of its proper divisors (1).

21395779587829 is an equidigital number, since it uses as much as digits as its factorization.

21395779587829 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4800902400, while the sum is 82.

The spelling of 21395779587829 in words is "twenty-one trillion, three hundred ninety-five billion, seven hundred seventy-nine million, five hundred eighty-seven thousand, eight hundred twenty-nine".