81871739 has 2 divisors, whose sum is σ = 81871740. Its totient is φ = 81871738.

The previous prime is 81871687. The next prime is 81871819. The reversal of 81871739 is 93717818.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81871739 - 2⁸ = 81871483 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81871739.

It is not a weakly prime, because it can be changed into another prime (81871939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40935869 + 40935870.

It is an arithmetic number, because the mean of its divisors is an integer number (40935870).

Almost surely, 2^81871739 is an apocalyptic number.

81871739 is a deficient number, since it is larger than the sum of its proper divisors (1).

81871739 is an equidigital number, since it uses as much as digits as its factorization.

81871739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 84672, while the sum is 44.

The square root of 81871739 is about 9048.3003376325. The cubic root of 81871739 is about 434.2215151121.

The spelling of 81871739 in words is "eighty-one million, eight hundred seventy-one thousand, seven hundred thirty-nine".