403981 has 2 divisors, whose sum is σ = 403982. Its totient is φ = 403980.

The previous prime is 403979. The next prime is 403993. The reversal of 403981 is 189304.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 401956 + 2025 = 634^2 + 45^2 .

It is a cyclic number.

It is not a de Polignac number, because 403981 - 2¹ = 403979 is a prime.

It is a super-2 number, since 2×403981² = 326401296722, which contains 22 as substring.

Together with 403979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (403901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201990 + 201991.

It is an arithmetic number, because the mean of its divisors is an integer number (201991).

2⁴⁰³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

403981 is a deficient number, since it is larger than the sum of its proper divisors (1).

403981 is an equidigital number, since it uses as much as digits as its factorization.

403981 is an evil number, because the sum of its binary digits is even.

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

The square root of 403981 is about 635.5949968337. The cubic root of 403981 is about 73.9242590022.

The spelling of 403981 in words is "four hundred three thousand, nine hundred eighty-one".