81576997 has 2 divisors, whose sum is σ = 81576998. Its totient is φ = 81576996.

The previous prime is 81576991. The next prime is 81577037. The reversal of 81576997 is 79967518.

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., 80263681 + 1313316 = 8959^2 + 1146^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81576997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81576991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40788498 + 40788499.

It is an arithmetic number, because the mean of its divisors is an integer number (40788499).

Almost surely, 2^81576997 is an apocalyptic number.

It is an amenable number.

81576997 is a deficient number, since it is larger than the sum of its proper divisors (1).

81576997 is an equidigital number, since it uses as much as digits as its factorization.

81576997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 952560, while the sum is 52.

The square root of 81576997 is about 9031.9985053143. The cubic root of 81576997 is about 433.6998161343.

The spelling of 81576997 in words is "eighty-one million, five hundred seventy-six thousand, nine hundred ninety-seven".