81700709 has 2 divisors, whose sum is σ = 81700710. Its totient is φ = 81700708.

The previous prime is 81700681. The next prime is 81700721. The reversal of 81700709 is 90700718.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50452609 + 31248100 = 7103^2 + 5590^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81700709 is a prime.

It is a super-2 number, since 2×81700709² = 13350011702205362, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81700789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40850354 + 40850355.

It is an arithmetic number, because the mean of its divisors is an integer number (40850355).

Almost surely, 2^81700709 is an apocalyptic number.

It is an amenable number.

81700709 is a deficient number, since it is larger than the sum of its proper divisors (1).

81700709 is an equidigital number, since it uses as much as digits as its factorization.

81700709 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3528, while the sum is 32.

The square root of 81700709 is about 9038.8444504815. The cubic root of 81700709 is about 433.9189415181.

Subtracting 81700709 from its reverse (90700718), we obtain a palindrome (9000009).

The spelling of 81700709 in words is "eighty-one million, seven hundred thousand, seven hundred nine".