81960013 has 4 divisors (see below), whose sum is σ = 81981468. Its totient is φ = 81938560.

The previous prime is 81959987. The next prime is 81960029. The reversal of 81960013 is 31006918.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31006918 = 2 ⋅15503459.

It can be written as a sum of positive squares in 2 ways, for example, as 43059844 + 38900169 = 6562^2 + 6237^2 .

It is a cyclic number.

It is not a de Polignac number, because 81960013 - 2⁵ = 81959981 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 (81960713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3268 + ... + 13213.

It is an arithmetic number, because the mean of its divisors is an integer number (20495367).

Almost surely, 2^81960013 is an apocalyptic number.

It is an amenable number.

81960013 is a deficient number, since it is larger than the sum of its proper divisors (21455).

81960013 is a wasteful number, since it uses less digits than its factorization.

81960013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21454.

The product of its (nonzero) digits is 1296, while the sum is 28.

The square root of 81960013 is about 9053.1769561850. The cubic root of 81960013 is about 434.3775180780.

The spelling of 81960013 in words is "eighty-one million, nine hundred sixty thousand, thirteen".