81156739 has 2 divisors, whose sum is σ = 81156740. Its totient is φ = 81156738.

The previous prime is 81156737. The next prime is 81156769. The reversal of 81156739 is 93765118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81156739 - 2¹ = 81156737 is a prime.

It is a super-2 number, since 2×81156739² = 13172832570228242, which contains 22 as substring.

Together with 81156737, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81156737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40578369 + 40578370.

It is an arithmetic number, because the mean of its divisors is an integer number (40578370).

Almost surely, 2^81156739 is an apocalyptic number.

81156739 is a deficient number, since it is larger than the sum of its proper divisors (1).

81156739 is an equidigital number, since it uses as much as digits as its factorization.

81156739 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 45360, while the sum is 40.

The square root of 81156739 is about 9008.7035138248. The cubic root of 81156739 is about 432.9537736868.

The spelling of 81156739 in words is "eighty-one million, one hundred fifty-six thousand, seven hundred thirty-nine".