21194262711821 has 2 divisors, whose sum is σ = 21194262711822. Its totient is φ = 21194262711820.

The previous prime is 21194262711767. The next prime is 21194262711889. The reversal of 21194262711821 is 12811726249112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15859151346025 + 5335111365796 = 3982355^2 + 2309786^2 .

It is a cyclic number.

It is not a de Polignac number, because 21194262711821 - 2⁴² = 16796216200717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21194262711221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10597131355910 + 10597131355911.

It is an arithmetic number, because the mean of its divisors is an integer number (10597131355911).

Almost surely, 2^{21194262711821} is an apocalyptic number.

It is an amenable number.

21194262711821 is a deficient number, since it is larger than the sum of its proper divisors (1).

21194262711821 is an equidigital number, since it uses as much as digits as its factorization.

21194262711821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 193536, while the sum is 47.

The spelling of 21194262711821 in words is "twenty-one trillion, one hundred ninety-four billion, two hundred sixty-two million, seven hundred eleven thousand, eight hundred twenty-one".