81737213 has 2 divisors, whose sum is σ = 81737214. Its totient is φ = 81737212.

The previous prime is 81737203. The next prime is 81737233. The reversal of 81737213 is 31273718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73908409 + 7828804 = 8597^2 + 2798^2 .

It is a cyclic number.

It is not a de Polignac number, because 81737213 - 2⁴ = 81737197 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81737213.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81737203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40868606 + 40868607.

It is an arithmetic number, because the mean of its divisors is an integer number (40868607).

Almost surely, 2^81737213 is an apocalyptic number.

It is an amenable number.

81737213 is a deficient number, since it is larger than the sum of its proper divisors (1).

81737213 is an equidigital number, since it uses as much as digits as its factorization.

81737213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 32.

The square root of 81737213 is about 9040.8635096433. The cubic root of 81737213 is about 433.9835571081.

The spelling of 81737213 in words is "eighty-one million, seven hundred thirty-seven thousand, two hundred thirteen".