43218325981 has 2 divisors, whose sum is σ = 43218325982. Its totient is φ = 43218325980.

The previous prime is 43218325979. The next prime is 43218325993. The reversal of 43218325981 is 18952381234.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 43133059225 + 85266756 = 207685^2 + 9234^2 .

It is a cyclic number.

It is not a de Polignac number, because 43218325981 - 2¹ = 43218325979 is a prime.

It is a super-2 number, since 2×43218325981² (a number of 22 digits) contains 22 as substring.

Together with 43218325979, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (43218325081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21609162990 + 21609162991.

It is an arithmetic number, because the mean of its divisors is an integer number (21609162991).

Almost surely, 2^43218325981 is an apocalyptic number.

It is an amenable number.

43218325981 is a deficient number, since it is larger than the sum of its proper divisors (1).

43218325981 is an equidigital number, since it uses as much as digits as its factorization.

43218325981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 414720, while the sum is 46.

The spelling of 43218325981 in words is "forty-three billion, two hundred eighteen million, three hundred twenty-five thousand, nine hundred eighty-one".