18553982981 has 2 divisors, whose sum is σ = 18553982982. Its totient is φ = 18553982980.

The previous prime is 18553982969. The next prime is 18553982983. The reversal of 18553982981 is 18928935581.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16443958756 + 2110024225 = 128234^2 + 45935^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18553982981 is a prime.

It is a super-2 number, since 2×18553982981² (a number of 21 digits) contains 22 as substring.

Together with 18553982983, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18553982981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18553982983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9276991490 + 9276991491.

It is an arithmetic number, because the mean of its divisors is an integer number (9276991491).

Almost surely, 2^18553982981 is an apocalyptic number.

It is an amenable number.

18553982981 is a deficient number, since it is larger than the sum of its proper divisors (1).

18553982981 is an equidigital number, since it uses as much as digits as its factorization.

18553982981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6220800, while the sum is 59.

The spelling of 18553982981 in words is "eighteen billion, five hundred fifty-three million, nine hundred eighty-two thousand, nine hundred eighty-one".