1981311 has 8 divisors (see below), whose sum is σ = 2703360. Its totient is φ = 1290072.

The previous prime is 1981297. The next prime is 1981337. The reversal of 1981311 is 1131891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1981311 - 2⁶ = 1981247 is a prime.

It is a super-3 number, since 3×1981311³ = 23333463433967949693, which contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981361) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7551 + ... + 7808.

It is an arithmetic number, because the mean of its divisors is an integer number (337920).

2^1981311 is an apocalyptic number.

1981311 is a deficient number, since it is larger than the sum of its proper divisors (722049).

1981311 is a wasteful number, since it uses less digits than its factorization.

1981311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15405.

The product of its digits is 216, while the sum is 24.

The square root of 1981311 is about 1407.5904944266. The cubic root of 1981311 is about 125.5984317965.

The spelling of 1981311 in words is "one million, nine hundred eighty-one thousand, three hundred eleven".