81159499 has 4 divisors (see below), whose sum is σ = 81188640. Its totient is φ = 81130360.

The previous prime is 81159497. The next prime is 81159509. The reversal of 81159499 is 99495118.

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 81159499 - 2¹ = 81159497 is a prime.

It is a super-3 number, since 3×81159499³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81159497) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9892 + ... + 16129.

It is an arithmetic number, because the mean of its divisors is an integer number (20297160).

Almost surely, 2^81159499 is an apocalyptic number.

81159499 is a deficient number, since it is larger than the sum of its proper divisors (29141).

81159499 is a wasteful number, since it uses less digits than its factorization.

81159499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29140.

The product of its digits is 116640, while the sum is 46.

The square root of 81159499 is about 9008.8566977170. The cubic root of 81159499 is about 432.9586816336.

The spelling of 81159499 in words is "eighty-one million, one hundred fifty-nine thousand, four hundred ninety-nine".