81079513 has 2 divisors, whose sum is σ = 81079514. Its totient is φ = 81079512.

The previous prime is 81079501. The next prime is 81079549. The reversal of 81079513 is 31597018.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 62520649 + 18558864 = 7907^2 + 4308^2 .

It is a cyclic number.

It is not a de Polignac number, because 81079513 - 2¹³ = 81071321 is a prime.

It is not a weakly prime, because it can be changed into another prime (81079013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539756 + 40539757.

It is an arithmetic number, because the mean of its divisors is an integer number (40539757).

Almost surely, 2^81079513 is an apocalyptic number.

It is an amenable number.

81079513 is a deficient number, since it is larger than the sum of its proper divisors (1).

81079513 is an equidigital number, since it uses as much as digits as its factorization.

81079513 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7560, while the sum is 34.

The square root of 81079513 is about 9004.4163053471. The cubic root of 81079513 is about 432.8164020631.

It can be divided in two parts, 8 and 1079513, that added together give a square (1079521 = 1039²).

The spelling of 81079513 in words is "eighty-one million, seventy-nine thousand, five hundred thirteen".