81161055 has 16 divisors (see below), whose sum is σ = 144286560. Its totient is φ = 43285824.

The previous prime is 81161051. The next prime is 81161063. The reversal of 81161055 is 55016118.

It is not a de Polignac number, because 81161055 - 2² = 81161051 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81161051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 300462 + ... + 300731.

It is an arithmetic number, because the mean of its divisors is an integer number (9017910).

Almost surely, 2^81161055 is an apocalyptic number.

81161055 is a deficient number, since it is larger than the sum of its proper divisors (63125505).

81161055 is a wasteful number, since it uses less digits than its factorization.

81161055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 601207 (or 601201 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 27.

The square root of 81161055 is about 9008.9430567631. The cubic root of 81161055 is about 432.9614485285.

The spelling of 81161055 in words is "eighty-one million, one hundred sixty-one thousand, fifty-five".