81598265789 has 4 divisors (see below), whose sum is σ = 82118000124. Its totient is φ = 81078531456.

The previous prime is 81598265759. The next prime is 81598265803. The reversal of 81598265789 is 98756289518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98756289518 = 2 ⋅49378144759.

It can be written as a sum of positive squares in 2 ways, for example, as 31455860164 + 50142405625 = 177358^2 + 223925^2 .

It is a cyclic number.

It is not a de Polignac number, because 81598265789 - 2¹⁶ = 81598200253 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81598265719) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 259866932 + ... + 259867245.

It is an arithmetic number, because the mean of its divisors is an integer number (20529500031).

Almost surely, 2^81598265789 is an apocalyptic number.

It is an amenable number.

81598265789 is a deficient number, since it is larger than the sum of its proper divisors (519734335).

81598265789 is a wasteful number, since it uses less digits than its factorization.

81598265789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 519734334.

The product of its digits is 87091200, while the sum is 68.

The spelling of 81598265789 in words is "eighty-one billion, five hundred ninety-eight million, two hundred sixty-five thousand, seven hundred eighty-nine".