81598409 has 2 divisors, whose sum is σ = 81598410. Its totient is φ = 81598408.

The previous prime is 81598393. The next prime is 81598423. The reversal of 81598409 is 90489518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 49392784 + 32205625 = 7028^2 + 5675^2 .

It is a cyclic number.

It is not a de Polignac number, because 81598409 - 2⁴ = 81598393 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81598409.

It is not a weakly prime, because it can be changed into another prime (81598009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40799204 + 40799205.

It is an arithmetic number, because the mean of its divisors is an integer number (40799205).

Almost surely, 2^81598409 is an apocalyptic number.

It is an amenable number.

81598409 is a deficient number, since it is larger than the sum of its proper divisors (1).

81598409 is an equidigital number, since it uses as much as digits as its factorization.

81598409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 44.

The square root of 81598409 is about 9033.1837687495. The cubic root of 81598409 is about 433.7377580723.

The spelling of 81598409 in words is "eighty-one million, five hundred ninety-eight thousand, four hundred nine".