393981 has 16 divisors (see below), whose sum is σ = 610944. Its totient is φ = 221184.

The previous prime is 393977. The next prime is 393989. The reversal of 393981 is 189393.

It is not a de Polignac number, because 393981 - 2² = 393977 is a prime.

It is a super-2 number, since 2×393981² = 310442056722, which contains 22 as substring.

393981 is a lucky number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 393981.

It is not an unprimeable number, because it can be changed into a prime (393989) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1405 + ... + 1661.

It is an arithmetic number, because the mean of its divisors is an integer number (38184).

2³⁹³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

393981 is a deficient number, since it is larger than the sum of its proper divisors (216963).

393981 is a wasteful number, since it uses less digits than its factorization.

393981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340.

The product of its digits is 5832, while the sum is 33.

The square root of 393981 is about 627.6790581181. The cubic root of 393981 is about 73.3091908590.

The spelling of 393981 in words is "three hundred ninety-three thousand, nine hundred eighty-one".