81261259 has 4 divisors (see below), whose sum is σ = 81387504. Its totient is φ = 81135016.

The previous prime is 81261251. The next prime is 81261281. The reversal of 81261259 is 95216218.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81261259 - 2³ = 81261251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81261251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 62152 + ... + 63445.

It is an arithmetic number, because the mean of its divisors is an integer number (20346876).

Almost surely, 2^81261259 is an apocalyptic number.

81261259 is a deficient number, since it is larger than the sum of its proper divisors (126245).

81261259 is a wasteful number, since it uses less digits than its factorization.

81261259 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126244.

The product of its digits is 8640, while the sum is 34.

The square root of 81261259 is about 9014.5027039765. The cubic root of 81261259 is about 433.1395578717.

The spelling of 81261259 in words is "eighty-one million, two hundred sixty-one thousand, two hundred fifty-nine".