81047513 has 2 divisors, whose sum is σ = 81047514. Its totient is φ = 81047512.

The previous prime is 81047503. The next prime is 81047531. The reversal of 81047513 is 31574018.

Together with next prime (81047531) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 44662489 + 36385024 = 6683^2 + 6032^2 .

It is a cyclic number.

It is not a de Polignac number, because 81047513 - 2⁴ = 81047497 is a prime.

It is not a weakly prime, because it can be changed into another prime (81047503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40523756 + 40523757.

It is an arithmetic number, because the mean of its divisors is an integer number (40523757).

Almost surely, 2^81047513 is an apocalyptic number.

It is an amenable number.

81047513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81047513 is an equidigital number, since it uses as much as digits as its factorization.

81047513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 81047513 is about 9002.6392241387. The cubic root of 81047513 is about 432.7594540670.

The spelling of 81047513 in words is "eighty-one million, forty-seven thousand, five hundred thirteen".