19918361 has 2 divisors, whose sum is σ = 19918362. Its totient is φ = 19918360.

The previous prime is 19918357. The next prime is 19918429. The reversal of 19918361 is 16381991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11971600 + 7946761 = 3460^2 + 2819^2 .

It is a cyclic number.

It is not a de Polignac number, because 19918361 - 2² = 19918357 is a prime.

It is a super-2 number, since 2×19918361² = 793482209852642, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19911361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9959180 + 9959181.

It is an arithmetic number, because the mean of its divisors is an integer number (9959181).

Almost surely, 2^19918361 is an apocalyptic number.

It is an amenable number.

19918361 is a deficient number, since it is larger than the sum of its proper divisors (1).

19918361 is an equidigital number, since it uses as much as digits as its factorization.

19918361 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 38.

The square root of 19918361 is about 4462.9991037418. Note that the first 3 decimals coincide. The cubic root of 19918361 is about 271.0719207450.

The spelling of 19918361 in words is "nineteen million, nine hundred eighteen thousand, three hundred sixty-one".