981581 has 8 divisors (see below), whose sum is σ = 1020600. Its totient is φ = 943360.

The previous prime is 981577. The next prime is 981587. The reversal of 981581 is 185189.

981581 = T₁₉₈ + T₁₉₉ + ... + T₂₃₈.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 96100 + 885481 = 310^2 + 941^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 981581 - 2² = 981577 is a prime.

It is a super-2 number, since 2×981581² = 1927002519122, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3515 + ... + 3783.

It is an arithmetic number, because the mean of its divisors is an integer number (127575).

2⁹⁸¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

981581 is a deficient number, since it is larger than the sum of its proper divisors (39019).

981581 is a wasteful number, since it uses less digits than its factorization.

981581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399.

The product of its digits is 2880, while the sum is 32.

The square root of 981581 is about 990.7476974488. The cubic root of 981581 is about 99.3822247295.

The spelling of 981581 in words is "nine hundred eighty-one thousand, five hundred eighty-one".