78561 has 24 divisors (see below), whose sum is σ = 137280. Its totient is φ = 42336.

The previous prime is 78553. The next prime is 78569. The reversal of 78561 is 16587.

It is an interprime number because it is at equal distance from previous prime (78553) and next prime (78569).

It is not a de Polignac number, because 78561 - 2³ = 78553 is a prime.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78569) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1806 + ... + 1848.

It is an arithmetic number, because the mean of its divisors is an integer number (5720).

2⁷⁸⁵⁶¹ is an apocalyptic number.

It is an amenable number.

78561 is a deficient number, since it is larger than the sum of its proper divisors (58719).

78561 is a wasteful number, since it uses less digits than its factorization.

78561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85 (or 82 counting only the distinct ones).

The product of its digits is 1680, while the sum is 27.

The square root of 78561 is about 280.2873525509. The cubic root of 78561 is about 42.8287764670.

The spelling of 78561 in words is "seventy-eight thousand, five hundred sixty-one".