81700231 has 2 divisors, whose sum is σ = 81700232. Its totient is φ = 81700230.

The previous prime is 81700207. The next prime is 81700237. The reversal of 81700231 is 13200718.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81700231 - 2¹⁵ = 81667463 is a prime.

It is a super-2 number, since 2×81700231² = 13349855490906722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81700237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40850115 + 40850116.

It is an arithmetic number, because the mean of its divisors is an integer number (40850116).

Almost surely, 2^81700231 is an apocalyptic number.

81700231 is a deficient number, since it is larger than the sum of its proper divisors (1).

81700231 is an equidigital number, since it uses as much as digits as its factorization.

81700231 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 81700231 is about 9038.8180090098. The cubic root of 81700231 is about 433.9180952845.

Adding to 81700231 its reverse (13200718), we get a palindrome (94900949).

The spelling of 81700231 in words is "eighty-one million, seven hundred thousand, two hundred thirty-one".