21164542377989 has 2 divisors, whose sum is σ = 21164542377990. Its totient is φ = 21164542377988.

The previous prime is 21164542377971. The next prime is 21164542378009. The reversal of 21164542377989 is 98977324546112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17529151889089 + 3635390488900 = 4186783^2 + 1906670^2 .

It is a cyclic number.

It is not a de Polignac number, because 21164542377989 - 2⁸ = 21164542377733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21164542377089) 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, 10582271188994 + 10582271188995.

It is an arithmetic number, because the mean of its divisors is an integer number (10582271188995).

Almost surely, 2^{21164542377989} is an apocalyptic number.

It is an amenable number.

21164542377989 is a deficient number, since it is larger than the sum of its proper divisors (1).

21164542377989 is an equidigital number, since it uses as much as digits as its factorization.

21164542377989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 182891520, while the sum is 68.

The spelling of 21164542377989 in words is "twenty-one trillion, one hundred sixty-four billion, five hundred forty-two million, three hundred seventy-seven thousand, nine hundred eighty-nine".