81413779 has 4 divisors (see below), whose sum is σ = 81447184. Its totient is φ = 81380376.

The previous prime is 81413747. The next prime is 81413789. The reversal of 81413779 is 97731418.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97731418 = 2 ⋅48865709.

It is a cyclic number.

It is not a de Polignac number, because 81413779 - 2⁵ = 81413747 is a prime.

It is a super-2 number, since 2×81413779² = 13256406822121682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81413789) 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, 12732 + ... + 18025.

It is an arithmetic number, because the mean of its divisors is an integer number (20361796).

Almost surely, 2^81413779 is an apocalyptic number.

81413779 is a deficient number, since it is larger than the sum of its proper divisors (33405).

81413779 is a wasteful number, since it uses less digits than its factorization.

81413779 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33404.

The product of its digits is 42336, while the sum is 40.

The square root of 81413779 is about 9022.9584394477. The cubic root of 81413779 is about 433.4103763739.

The spelling of 81413779 in words is "eighty-one million, four hundred thirteen thousand, seven hundred seventy-nine".