263981 has 4 divisors (see below), whose sum is σ = 265212. Its totient is φ = 262752.

The previous prime is 263957. The next prime is 263983. The reversal of 263981 is 189362.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 75625 + 188356 = 275^2 + 434^2 .

It is a cyclic number.

It is not a de Polignac number, because 263981 - 2¹⁰ = 262957 is a prime.

It is a super-2 number, since 2×263981² = 139371936722, which contains 22 as substring.

It is a Duffinian 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 263981.

It is not an unprimeable number, because it can be changed into a prime (263983) 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, 200 + ... + 753.

It is an arithmetic number, because the mean of its divisors is an integer number (66303).

2²⁶³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

263981 is a deficient number, since it is larger than the sum of its proper divisors (1231).

263981 is an equidigital number, since it uses as much as digits as its factorization.

263981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1230.

The product of its digits is 2592, while the sum is 29.

The square root of 263981 is about 513.7908134640. The cubic root of 263981 is about 64.1491475945.

The spelling of 263981 in words is "two hundred sixty-three thousand, nine hundred eighty-one".