81589650973 has 2 divisors, whose sum is σ = 81589650974. Its totient is φ = 81589650972.

The previous prime is 81589650959. The next prime is 81589650977. The reversal of 81589650973 is 37905698518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 74789669529 + 6799981444 = 273477^2 + 82462^2 .

It is a cyclic number.

It is not a de Polignac number, because 81589650973 - 2³³ = 72999716381 is a prime.

It is a super-2 number, since 2×81589650973² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81589650977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40794825486 + 40794825487.

It is an arithmetic number, because the mean of its divisors is an integer number (40794825487).

Almost surely, 2^81589650973 is an apocalyptic number.

It is an amenable number.

81589650973 is a deficient number, since it is larger than the sum of its proper divisors (1).

81589650973 is an equidigital number, since it uses as much as digits as its factorization.

81589650973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16329600, while the sum is 61.

The spelling of 81589650973 in words is "eighty-one billion, five hundred eighty-nine million, six hundred fifty thousand, nine hundred seventy-three".