21162566729 has 2 divisors, whose sum is σ = 21162566730. Its totient is φ = 21162566728.

The previous prime is 21162566717. The next prime is 21162566759. The reversal of 21162566729 is 92766526112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11450070025 + 9712496704 = 107005^2 + 98552^2 .

It is a cyclic number.

It is not a de Polignac number, because 21162566729 - 2⁸ = 21162566473 is a prime.

It is a super-3 number, since 3×21162566729³ (a number of 32 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21162566759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10581283364 + 10581283365.

It is an arithmetic number, because the mean of its divisors is an integer number (10581283365).

Almost surely, 2^21162566729 is an apocalyptic number.

It is an amenable number.

21162566729 is a deficient number, since it is larger than the sum of its proper divisors (1).

21162566729 is an equidigital number, since it uses as much as digits as its factorization.

21162566729 is an evil number, because the sum of its binary digits is even.

The product of its digits is 544320, while the sum is 47.

The spelling of 21162566729 in words is "twenty-one billion, one hundred sixty-two million, five hundred sixty-six thousand, seven hundred twenty-nine".