5581981 has 4 divisors (see below), whose sum is σ = 5606172. Its totient is φ = 5557792.

The previous prime is 5581973. The next prime is 5582009. The reversal of 5581981 is 1891855.

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 2859481 + 2722500 = 1691^2 + 1650^2 .

It is a cyclic number.

It is not a de Polignac number, because 5581981 - 2³ = 5581973 is a prime.

It is a super-2 number, since 2×5581981² = 62317023768722, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 5581981.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (5581181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11746 + ... + 12211.

It is an arithmetic number, because the mean of its divisors is an integer number (1401543).

Almost surely, 2^5581981 is an apocalyptic number.

It is an amenable number.

5581981 is a deficient number, since it is larger than the sum of its proper divisors (24191).

5581981 is a wasteful number, since it uses less digits than its factorization.

5581981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24190.

The product of its digits is 14400, while the sum is 37.

The square root of 5581981 is about 2362.6216370803. The cubic root of 5581981 is about 177.3901297178.

The spelling of 5581981 in words is "five million, five hundred eighty-one thousand, nine hundred eighty-one".