21259164761 has 2 divisors, whose sum is σ = 21259164762. Its totient is φ = 21259164760.

The previous prime is 21259164743. The next prime is 21259164803. The reversal of 21259164761 is 16746195212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13058775625 + 8200389136 = 114275^2 + 90556^2 .

It is a cyclic number.

It is not a de Polignac number, because 21259164761 - 2¹⁸ = 21258902617 is a prime.

It is not a weakly prime, because it can be changed into another prime (21259164721) 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, 10629582380 + 10629582381.

It is an arithmetic number, because the mean of its divisors is an integer number (10629582381).

Almost surely, 2^21259164761 is an apocalyptic number.

It is an amenable number.

21259164761 is a deficient number, since it is larger than the sum of its proper divisors (1).

21259164761 is an equidigital number, since it uses as much as digits as its factorization.

21259164761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 181440, while the sum is 44.

The spelling of 21259164761 in words is "twenty-one billion, two hundred fifty-nine million, one hundred sixty-four thousand, seven hundred sixty-one".