81387049 has 2 divisors, whose sum is σ = 81387050. Its totient is φ = 81387048.

The previous prime is 81386999. The next prime is 81387067. The reversal of 81387049 is 94078318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 45805824 + 35581225 = 6768^2 + 5965^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81387049 is a prime.

It is equal to p_4745776 and since 81387049 and 4745776 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (81387749) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40693524 + 40693525.

It is an arithmetic number, because the mean of its divisors is an integer number (40693525).

Almost surely, 2^81387049 is an apocalyptic number.

It is an amenable number.

81387049 is a deficient number, since it is larger than the sum of its proper divisors (1).

81387049 is an equidigital number, since it uses as much as digits as its factorization.

81387049 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48384, while the sum is 40.

The square root of 81387049 is about 9021.4770963518. The cubic root of 81387049 is about 433.3629383455.

The spelling of 81387049 in words is "eighty-one million, three hundred eighty-seven thousand, forty-nine".