18981617 has 2 divisors, whose sum is σ = 18981618. Its totient is φ = 18981616.

The previous prime is 18981583. The next prime is 18981649. The reversal of 18981617 is 71618981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15124321 + 3857296 = 3889^2 + 1964^2 .

It is a cyclic number.

It is not a de Polignac number, because 18981617 - 2¹² = 18977521 is a prime.

It is not a weakly prime, because it can be changed into another prime (18981667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9490808 + 9490809.

It is an arithmetic number, because the mean of its divisors is an integer number (9490809).

Almost surely, 2^18981617 is an apocalyptic number.

It is an amenable number.

18981617 is a deficient number, since it is larger than the sum of its proper divisors (1).

18981617 is an equidigital number, since it uses as much as digits as its factorization.

18981617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 41.

The square root of 18981617 is about 4356.7897585263. The cubic root of 18981617 is about 266.7540788088.

The spelling of 18981617 in words is "eighteen million, nine hundred eighty-one thousand, six hundred seventeen".