81689677 has 2 divisors, whose sum is σ = 81689678. Its totient is φ = 81689676.

The previous prime is 81689669. The next prime is 81689711. The reversal of 81689677 is 77698618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69655716 + 12033961 = 8346^2 + 3469^2 .

It is a cyclic number.

It is not a de Polignac number, because 81689677 - 2³ = 81689669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81689177) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40844838 + 40844839.

It is an arithmetic number, because the mean of its divisors is an integer number (40844839).

Almost surely, 2^81689677 is an apocalyptic number.

It is an amenable number.

81689677 is a deficient number, since it is larger than the sum of its proper divisors (1).

81689677 is an equidigital number, since it uses as much as digits as its factorization.

81689677 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1016064, while the sum is 52.

The square root of 81689677 is about 9038.2341748817. The cubic root of 81689677 is about 433.8994100302.

The spelling of 81689677 in words is "eighty-one million, six hundred eighty-nine thousand, six hundred seventy-seven".