81780159 has 4 divisors (see below), whose sum is σ = 109040216. Its totient is φ = 54520104.

The previous prime is 81780151. The next prime is 81780169. The reversal of 81780159 is 95108718.

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

It is not a de Polignac number, because 81780159 - 2³ = 81780151 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81780151) 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, 13630024 + ... + 13630029.

It is an arithmetic number, because the mean of its divisors is an integer number (27260054).

Almost surely, 2^81780159 is an apocalyptic number.

81780159 is a deficient number, since it is larger than the sum of its proper divisors (27260057).

81780159 is a wasteful number, since it uses less digits than its factorization.

81780159 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27260056.

The product of its (nonzero) digits is 20160, while the sum is 39.

The square root of 81780159 is about 9043.2383027320. The cubic root of 81780159 is about 434.0595510319.

The spelling of 81780159 in words is "eighty-one million, seven hundred eighty thousand, one hundred fifty-nine".