81513259 has 2 divisors, whose sum is σ = 81513260. Its totient is φ = 81513258.

The previous prime is 81513241. The next prime is 81513319. The reversal of 81513259 is 95231518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81513259 - 2¹¹ = 81511211 is a prime.

It is a super-2 number, since 2×81513259² = 13288822785602162, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81513209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40756629 + 40756630.

It is an arithmetic number, because the mean of its divisors is an integer number (40756630).

Almost surely, 2^81513259 is an apocalyptic number.

81513259 is a deficient number, since it is larger than the sum of its proper divisors (1).

81513259 is an equidigital number, since it uses as much as digits as its factorization.

81513259 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10800, while the sum is 34.

The square root of 81513259 is about 9028.4693608607. The cubic root of 81513259 is about 433.5868334617.

The spelling of 81513259 in words is "eighty-one million, five hundred thirteen thousand, two hundred fifty-nine".