81726691 has 2 divisors, whose sum is σ = 81726692. Its totient is φ = 81726690.

The previous prime is 81726683. The next prime is 81726731. The reversal of 81726691 is 19662718.

It is an a-pointer prime, because the next prime (81726731) can be obtained adding 81726691 to its sum of digits (40).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81726691 - 2³ = 81726683 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81726661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40863345 + 40863346.

It is an arithmetic number, because the mean of its divisors is an integer number (40863346).

Almost surely, 2^81726691 is an apocalyptic number.

81726691 is a deficient number, since it is larger than the sum of its proper divisors (1).

81726691 is an equidigital number, since it uses as much as digits as its factorization.

81726691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36288, while the sum is 40.

The square root of 81726691 is about 9040.2815774731. The cubic root of 81726691 is about 433.9649341302.

The spelling of 81726691 in words is "eighty-one million, seven hundred twenty-six thousand, six hundred ninety-one".