81555556297 has 4 divisors (see below), whose sum is σ = 82704226176. Its totient is φ = 80406886420.

The previous prime is 81555556279. The next prime is 81555556301. The reversal of 81555556297 is 79265555518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81555556297 is a prime.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81555556207) 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, 574334833 + ... + 574334974.

It is an arithmetic number, because the mean of its divisors is an integer number (20676056544).

Almost surely, 2^81555556297 is an apocalyptic number.

It is an amenable number.

81555556297 is a deficient number, since it is larger than the sum of its proper divisors (1148669879).

81555556297 is a wasteful number, since it uses less digits than its factorization.

81555556297 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1148669878.

The product of its digits is 18900000, while the sum is 58.

The spelling of 81555556297 in words is "eighty-one billion, five hundred fifty-five million, five hundred fifty-six thousand, two hundred ninety-seven".