81642797 has 2 divisors, whose sum is σ = 81642798. Its totient is φ = 81642796.

The previous prime is 81642773. The next prime is 81642833. The reversal of 81642797 is 79724618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50495236 + 31147561 = 7106^2 + 5581^2 .

It is a cyclic number.

It is not a de Polignac number, because 81642797 - 2⁶ = 81642733 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81642707) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40821398 + 40821399.

It is an arithmetic number, because the mean of its divisors is an integer number (40821399).

Almost surely, 2^81642797 is an apocalyptic number.

It is an amenable number.

81642797 is a deficient number, since it is larger than the sum of its proper divisors (1).

81642797 is an equidigital number, since it uses as much as digits as its factorization.

81642797 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 44.

The square root of 81642797 is about 9035.6403757564. The cubic root of 81642797 is about 433.8163922101.

The spelling of 81642797 in words is "eighty-one million, six hundred forty-two thousand, seven hundred ninety-seven".