1818981 has 6 divisors (see below), whose sum is σ = 2627430. Its totient is φ = 1212648.

The previous prime is 1818979. The next prime is 1818989. The reversal of 1818981 is 1898181.

It can be written as a sum of positive squares in only one way, i.e., 1602756 + 216225 = 1266^2 + 465^2 .

It is not a de Polignac number, because 1818981 - 2¹ = 1818979 is a prime.

It is a super-2 number, since 2×1818981² = 6617383756722, which contains 22 as substring.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1818989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 101046 + ... + 101063.

It is an arithmetic number, because the mean of its divisors is an integer number (437905).

2^1818981 is an apocalyptic number.

It is an amenable number.

1818981 is a deficient number, since it is larger than the sum of its proper divisors (808449).

1818981 is a wasteful number, since it uses less digits than its factorization.

1818981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202115 (or 202112 counting only the distinct ones).

The product of its digits is 4608, while the sum is 36.

The square root of 1818981 is about 1348.6960369186. The cubic root of 1818981 is about 122.0701245156.

The spelling of 1818981 in words is "one million, eight hundred eighteen thousand, nine hundred eighty-one".