81171773953 has 2 divisors, whose sum is σ = 81171773954. Its totient is φ = 81171773952.

The previous prime is 81171773929. The next prime is 81171773993. The reversal of 81171773953 is 35937717118.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72647499024 + 8524274929 = 269532^2 + 92327^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81171773953 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81171773953.

It is not a weakly prime, because it can be changed into another prime (81171773993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40585886976 + 40585886977.

It is an arithmetic number, because the mean of its divisors is an integer number (40585886977).

Almost surely, 2^81171773953 is an apocalyptic number.

It is an amenable number.

81171773953 is a deficient number, since it is larger than the sum of its proper divisors (1).

81171773953 is an equidigital number, since it uses as much as digits as its factorization.

81171773953 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1111320, while the sum is 52.

The spelling of 81171773953 in words is "eighty-one billion, one hundred seventy-one million, seven hundred seventy-three thousand, nine hundred fifty-three".