43981 has 8 divisors (see below), whose sum is σ = 51584. Its totient is φ = 36720.

The previous prime is 43973. The next prime is 43987. The reversal of 43981 is 18934.

43981 is an esthetic number in base 16, because in such base its adjacent digits differ by 1.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 43981 - 2³ = 43973 is a prime.

It is a super-2 number, since 2×43981² = 3868656722, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

43981 is a lucky number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (43987) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 376 + ... + 478.

It is an arithmetic number, because the mean of its divisors is an integer number (6448).

2⁴³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

43981 is a deficient number, since it is larger than the sum of its proper divisors (7603).

43981 is a wasteful number, since it uses less digits than its factorization.

43981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171.

The product of its digits is 864, while the sum is 25.

The square root of 43981 is about 209.7164752708. The cubic root of 43981 is about 35.2984010597.

Subtracting from 43981 its sum of digits (25), we obtain a triangular number (43956 = T₂₉₆).

It can be divided in two parts, 43 and 981, that added together give a 10-th power (1024 = 2¹⁰).

The spelling of 43981 in words is "forty-three thousand, nine hundred eighty-one".