81661159 has 2 divisors, whose sum is σ = 81661160. Its totient is φ = 81661158.

The previous prime is 81661123. The next prime is 81661189. The reversal of 81661159 is 95116618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81661159 - 2¹⁷ = 81530087 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81661189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40830579 + 40830580.

It is an arithmetic number, because the mean of its divisors is an integer number (40830580).

Almost surely, 2^81661159 is an apocalyptic number.

81661159 is a deficient number, since it is larger than the sum of its proper divisors (1).

81661159 is an equidigital number, since it uses as much as digits as its factorization.

81661159 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 37.

The square root of 81661159 is about 9036.6564059944. The cubic root of 81661159 is about 433.8489124886.

The spelling of 81661159 in words is "eighty-one million, six hundred sixty-one thousand, one hundred fifty-nine".