185981 has 4 divisors (see below), whose sum is σ = 187200. Its totient is φ = 184764.

The previous prime is 185971. The next prime is 185987. The reversal of 185981 is 189581.

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.

It is a cyclic number.

It is not a de Polignac number, because 185981 - 2⁶ = 185917 is a prime.

It is a super-2 number, since 2×185981² = 69177864722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (185987) 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, 341 + ... + 698.

It is an arithmetic number, because the mean of its divisors is an integer number (46800).

2¹⁸⁵⁹⁸¹ is an apocalyptic number.

It is an amenable number.

185981 is a deficient number, since it is larger than the sum of its proper divisors (1219).

185981 is a wasteful number, since it uses less digits than its factorization.

185981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1218.

The product of its digits is 2880, while the sum is 32.

The square root of 185981 is about 431.2551448968. The cubic root of 185981 is about 57.0807309924.

Subtracting 185981 from its reverse (189581), we obtain a square (3600 = 60²).

The spelling of 185981 in words is "one hundred eighty-five thousand, nine hundred eighty-one".