1981313 has 4 divisors (see below), whose sum is σ = 2034900. Its totient is φ = 1927728.

The previous prime is 1981297. The next prime is 1981337. The reversal of 1981313 is 3131891.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 744769 + 1236544 = 863^2 + 1112^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981313 - 2⁴ = 1981297 is a prime.

It is a super-3 number, since 3×1981313³ = 23333534094718293891, which contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1981393) 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 3 ways as a sum of consecutive naturals, for example, 26738 + ... + 26811.

It is an arithmetic number, because the mean of its divisors is an integer number (508725).

2^1981313 is an apocalyptic number.

It is an amenable number.

1981313 is a deficient number, since it is larger than the sum of its proper divisors (53587).

1981313 is an equidigital number, since it uses as much as digits as its factorization.

1981313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53586.

The product of its digits is 648, while the sum is 26.

The square root of 1981313 is about 1407.5912048603. The cubic root of 1981313 is about 125.5984740575.

The spelling of 1981313 in words is "one million, nine hundred eighty-one thousand, three hundred thirteen".