81379619 has 4 divisors (see below), whose sum is σ = 84004800. Its totient is φ = 78754440.

The previous prime is 81379609. The next prime is 81379631. The reversal of 81379619 is 91697318.

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 81379619 - 2¹² = 81375523 is a prime.

It is a super-2 number, since 2×81379619² = 13245284777170322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81379619.

It is not an unprimeable number, because it can be changed into a prime (81379609) 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, 1312544 + ... + 1312605.

It is an arithmetic number, because the mean of its divisors is an integer number (21001200).

Almost surely, 2^81379619 is an apocalyptic number.

81379619 is a deficient number, since it is larger than the sum of its proper divisors (2625181).

81379619 is a wasteful number, since it uses less digits than its factorization.

81379619 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2625180.

The product of its digits is 81648, while the sum is 44.

The square root of 81379619 is about 9021.0652918599. The cubic root of 81379619 is about 433.3497503971.

The spelling of 81379619 in words is "eighty-one million, three hundred seventy-nine thousand, six hundred nineteen".