1981180561 has 8 divisors (see below), whose sum is σ = 2098119240. Its totient is φ = 1864286208.

The previous prime is 1981180517. The next prime is 1981180567. The reversal of 1981180561 is 1650811891.

It can be written as a sum of positive squares in 4 ways, for example, as 855913536 + 1125267025 = 29256^2 + 33545^2 .

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 1981180561 - 2⁷ = 1981180433 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981180567) 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, 139585 + ... + 153121.

It is an arithmetic number, because the mean of its divisors is an integer number (262264905).

Almost surely, 2^1981180561 is an apocalyptic number.

It is an amenable number.

1981180561 is a deficient number, since it is larger than the sum of its proper divisors (116938679).

1981180561 is a wasteful number, since it uses less digits than its factorization.

1981180561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22163.

The product of its (nonzero) digits is 17280, while the sum is 40.

The square root of 1981180561 is about 44510.4545135185. The cubic root of 1981180561 is about 1255.9567549126.

The spelling of 1981180561 in words is "one billion, nine hundred eighty-one million, one hundred eighty thousand, five hundred sixty-one".