1981217 has 6 divisors (see below), whose sum is σ = 2304738. Its totient is φ = 1698144.

The previous prime is 1981201. The next prime is 1981237. The reversal of 1981217 is 7121891.

It can be written as a sum of positive squares in only one way, i.e., 1366561 + 614656 = 1169^2 + 784^2 .

It is not a de Polignac number, because 1981217 - 2⁴ = 1981201 is a prime.

It is a super-3 number, since 3×1981217³ = 23330142539613435939, which contains 333 as substring.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 1981217.

It is not an unprimeable number, because it can be changed into a prime (1981237) 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, 20168 + ... + 20265.

It is an arithmetic number, because the mean of its divisors is an integer number (384123).

2^1981217 is an apocalyptic number.

It is an amenable number.

1981217 is a deficient number, since it is larger than the sum of its proper divisors (323521).

1981217 is an equidigital number, since it uses as much as digits as its factorization.

1981217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40447 (or 40440 counting only the distinct ones).

The product of its digits is 1008, while the sum is 29.

The square root of 1981217 is about 1407.5571036374. The cubic root of 1981217 is about 125.5964454956.

The spelling of 1981217 in words is "one million, nine hundred eighty-one thousand, two hundred seventeen".