20344457981 has 2 divisors, whose sum is σ = 20344457982. Its totient is φ = 20344457980.

The previous prime is 20344457953. The next prime is 20344457983. The reversal of 20344457981 is 18975444302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20344457956 + 25 = 142634^2 + 5^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20344457981 is a prime.

It is a super-2 number, since 2×20344457981² (a number of 21 digits) contains 22 as substring.

Together with 20344457983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20344457983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10172228990 + 10172228991.

It is an arithmetic number, because the mean of its divisors is an integer number (10172228991).

Almost surely, 2^20344457981 is an apocalyptic number.

It is an amenable number.

20344457981 is a deficient number, since it is larger than the sum of its proper divisors (1).

20344457981 is an equidigital number, since it uses as much as digits as its factorization.

20344457981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 967680, while the sum is 47.

The spelling of 20344457981 in words is "twenty billion, three hundred forty-four million, four hundred fifty-seven thousand, nine hundred eighty-one".