813981 has 16 divisors (see below), whose sum is σ = 1257984. Its totient is φ = 458544.

The previous prime is 813971. The next prime is 813991. The reversal of 813981 is 189318.

It is an interprime number because it is at equal distance from previous prime (813971) and next prime (813991).

It is not a de Polignac number, because 813981 - 2¹¹ = 811933 is a prime.

It is a super-2 number, since 2×813981² = 1325130136722, which contains 22 as substring.

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 813981.

It is not an unprimeable number, because it can be changed into a prime (813931) 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, 1510 + ... + 1976.

It is an arithmetic number, because the mean of its divisors is an integer number (78624).

2⁸¹³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

813981 is a deficient number, since it is larger than the sum of its proper divisors (444003).

813981 is a wasteful number, since it uses less digits than its factorization.

813981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560.

The product of its digits is 1728, while the sum is 30.

The square root of 813981 is about 902.2089558412. The cubic root of 813981 is about 93.3694403949.

The spelling of 813981 in words is "eight hundred thirteen thousand, nine hundred eighty-one".