81191061 has 48 divisors (see below), whose sum is σ = 140153728. Its totient is φ = 44323200.

The previous prime is 81191057. The next prime is 81191083. The reversal of 81191061 is 16019118.

It is not a de Polignac number, because 81191061 - 2² = 81191057 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81191861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 141906 + ... + 142476.

Almost surely, 2^81191061 is an apocalyptic number.

It is an amenable number.

81191061 is a deficient number, since it is larger than the sum of its proper divisors (58962667).

81191061 is a wasteful number, since it uses less digits than its factorization.

81191061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 682 (or 679 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 27.

The square root of 81191061 is about 9010.6082480596. The cubic root of 81191061 is about 433.0147985847.

It can be divided in two parts, 8119 and 1061, that added together give a triangular number (9180 = T₁₃₅).

The spelling of 81191061 in words is "eighty-one million, one hundred ninety-one thousand, sixty-one".