1981610321 has 4 divisors (see below), whose sum is σ = 2098175652. Its totient is φ = 1865044992.

The previous prime is 1981610273. The next prime is 1981610327. The reversal of 1981610321 is 1230161891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1230161891 = 7 ⋅175737413.

It can be written as a sum of positive squares in 2 ways, for example, as 1645438096 + 336172225 = 40564^2 + 18335^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1981610321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981610327) 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, 58282640 + ... + 58282673.

It is an arithmetic number, because the mean of its divisors is an integer number (524543913).

Almost surely, 2^1981610321 is an apocalyptic number.

It is an amenable number.

1981610321 is a deficient number, since it is larger than the sum of its proper divisors (116565331).

1981610321 is a wasteful number, since it uses less digits than its factorization.

1981610321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116565330.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 1981610321 is about 44515.2818816190. The cubic root of 1981610321 is about 1256.0475628820.

The spelling of 1981610321 in words is "one billion, nine hundred eighty-one million, six hundred ten thousand, three hundred twenty-one".