81316889 has 2 divisors, whose sum is σ = 81316890. Its totient is φ = 81316888.

The previous prime is 81316877. The next prime is 81316919. The reversal of 81316889 is 98861318.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71910400 + 9406489 = 8480^2 + 3067^2 .

It is a cyclic number.

It is not a de Polignac number, because 81316889 - 2²⁰ = 80268313 is a prime.

It is a super-2 number, since 2×81316889² = 13224872873276642, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81316849) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40658444 + 40658445.

It is an arithmetic number, because the mean of its divisors is an integer number (40658445).

Almost surely, 2^81316889 is an apocalyptic number.

It is an amenable number.

81316889 is a deficient number, since it is larger than the sum of its proper divisors (1).

81316889 is an equidigital number, since it uses as much as digits as its factorization.

81316889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 82944, while the sum is 44.

The square root of 81316889 is about 9017.5877594842. The cubic root of 81316889 is about 433.2383751824.

The spelling of 81316889 in words is "eighty-one million, three hundred sixteen thousand, eight hundred eighty-nine".