81197755 has 4 divisors (see below), whose sum is σ = 97437312. Its totient is φ = 64958200.

The previous prime is 81197689. The next prime is 81197759. The reversal of 81197755 is 55779118.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-81197755 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81197759) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8119771 + ... + 8119780.

It is an arithmetic number, because the mean of its divisors is an integer number (24359328).

Almost surely, 2^81197755 is an apocalyptic number.

81197755 is a deficient number, since it is larger than the sum of its proper divisors (16239557).

81197755 is a wasteful number, since it uses less digits than its factorization.

81197755 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16239556.

The product of its digits is 88200, while the sum is 43.

The square root of 81197755 is about 9010.9796914653. The cubic root of 81197755 is about 433.0266985868.

The spelling of 81197755 in words is "eighty-one million, one hundred ninety-seven thousand, seven hundred fifty-five".