1981430581 has 4 divisors (see below), whose sum is σ = 2133848332. Its totient is φ = 1829012832.

The previous prime is 1981430579. The next prime is 1981430587. The reversal of 1981430581 is 1850341891.

It is a happy number.

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 985018225 + 996412356 = 31385^2 + 31566^2 .

It is a cyclic number.

It is not a de Polignac number, because 1981430581 - 2¹ = 1981430579 is a prime.

It is a super-3 number, since 3×1981430581³ (a number of 29 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1981430587) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76208856 + ... + 76208881.

It is an arithmetic number, because the mean of its divisors is an integer number (533462083).

Almost surely, 2^1981430581 is an apocalyptic number.

It is an amenable number.

1981430581 is a deficient number, since it is larger than the sum of its proper divisors (152417751).

1981430581 is a wasteful number, since it uses less digits than its factorization.

1981430581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152417750.

The product of its (nonzero) digits is 34560, while the sum is 40.

The square root of 1981430581 is about 44513.2629785775. The cubic root of 1981430581 is about 1256.0095855507.

The spelling of 1981430581 in words is "one billion, nine hundred eighty-one million, four hundred thirty thousand, five hundred eighty-one".