81655157 has 2 divisors, whose sum is σ = 81655158. Its totient is φ = 81655156.

The previous prime is 81655153. The next prime is 81655159. The reversal of 81655157 is 75155618.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 71757841 + 9897316 = 8471^2 + 3146^2 .

It is a cyclic number.

It is not a de Polignac number, because 81655157 - 2² = 81655153 is a prime.

It is a super-3 number, since 3×81655157³ (a number of 25 digits) contains 333 as substring.

Together with 81655159, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81655157.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81655153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40827578 + 40827579.

It is an arithmetic number, because the mean of its divisors is an integer number (40827579).

Almost surely, 2^81655157 is an apocalyptic number.

It is an amenable number.

81655157 is a deficient number, since it is larger than the sum of its proper divisors (1).

81655157 is an equidigital number, since it uses as much as digits as its factorization.

81655157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42000, while the sum is 38.

The square root of 81655157 is about 9036.3243080359. The cubic root of 81655157 is about 433.8382830984.

The spelling of 81655157 in words is "eighty-one million, six hundred fifty-five thousand, one hundred fifty-seven".