801981 has 10 divisors (see below), whose sum is σ = 1198142. Its totient is φ = 534600.

The previous prime is 801973. The next prime is 801989. The reversal of 801981 is 189108.

It is an interprime number because it is at equal distance from previous prime (801973) and next prime (801989).

It can be written as a sum of positive squares in only one way, i.e., 793881 + 8100 = 891^2 + 90^2 .

It is not a de Polignac number, because 801981 - 2³ = 801973 is a prime.

It is a super-2 number, since 2×801981² = 1286347048722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (801989) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4870 + ... + 5031.

2⁸⁰¹⁹⁸¹ is an apocalyptic number.

801981 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

801981 is a deficient number, since it is larger than the sum of its proper divisors (396161).

801981 is an equidigital number, since it uses as much as digits as its factorization.

801981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9913 (or 9904 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 27.

The square root of 801981 is about 895.5339189556. The cubic root of 801981 is about 92.9083384073.

It can be divided in two parts, 8019 and 81, that added together give a square (8100 = 90²).

The spelling of 801981 in words is "eight hundred one thousand, nine hundred eighty-one".