1981324817 has 2 divisors, whose sum is σ = 1981324818. Its totient is φ = 1981324816.

The previous prime is 1981324759. The next prime is 1981324831. The reversal of 1981324817 is 7184231891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1553621056 + 427703761 = 39416^2 + 20681^2 .

It is an emirp because it is prime and its reverse (7184231891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1981324817 - 2²⁸ = 1712889361 is a prime.

It is a super-3 number, since 3×1981324817³ (a number of 29 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (1981324837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990662408 + 990662409.

It is an arithmetic number, because the mean of its divisors is an integer number (990662409).

Almost surely, 2^1981324817 is an apocalyptic number.

It is an amenable number.

1981324817 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981324817 is an equidigital number, since it uses as much as digits as its factorization.

1981324817 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 44.

The square root of 1981324817 is about 44512.0749572518. The cubic root of 1981324817 is about 1255.9872375625.

The spelling of 1981324817 in words is "one billion, nine hundred eighty-one million, three hundred twenty-four thousand, eight hundred seventeen".