78581 has 4 divisors (see below), whose sum is σ = 79200. Its totient is φ = 77964.

The previous prime is 78577. The next prime is 78583. The reversal of 78581 is 18587.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 78581 - 2² = 78577 is a prime.

It is a super-2 number, since 2×78581² = 12349947122, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78583) 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, 41 + ... + 398.

It is an arithmetic number, because the mean of its divisors is an integer number (19800).

2⁷⁸⁵⁸¹ is an apocalyptic number.

It is an amenable number.

78581 is a deficient number, since it is larger than the sum of its proper divisors (619).

78581 is a wasteful number, since it uses less digits than its factorization.

78581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618.

The product of its digits is 2240, while the sum is 29.

The square root of 78581 is about 280.3230279517. The cubic root of 78581 is about 42.8324105978.

The spelling of 78581 in words is "seventy-eight thousand, five hundred eighty-one".