81797321 has 2 divisors, whose sum is σ = 81797322. Its totient is φ = 81797320.

The previous prime is 81797297. The next prime is 81797329. The reversal of 81797321 is 12379718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81360400 + 436921 = 9020^2 + 661^2 .

It is a cyclic number.

It is not a de Polignac number, because 81797321 - 2²² = 77603017 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81797329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40898660 + 40898661.

It is an arithmetic number, because the mean of its divisors is an integer number (40898661).

Almost surely, 2^81797321 is an apocalyptic number.

It is an amenable number.

81797321 is a deficient number, since it is larger than the sum of its proper divisors (1).

81797321 is an equidigital number, since it uses as much as digits as its factorization.

81797321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21168, while the sum is 38.

The square root of 81797321 is about 9044.1871387096. The cubic root of 81797321 is about 434.0899121409.

The spelling of 81797321 in words is "eighty-one million, seven hundred ninety-seven thousand, three hundred twenty-one".