18221661593 has 2 divisors, whose sum is σ = 18221661594. Its totient is φ = 18221661592.

The previous prime is 18221661587. The next prime is 18221661629. The reversal of 18221661593 is 39516612281.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13659064384 + 4562597209 = 116872^2 + 67547^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18221661593 is a prime.

It is a super-2 number, since 2×18221661593² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18221661533) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9110830796 + 9110830797.

It is an arithmetic number, because the mean of its divisors is an integer number (9110830797).

Almost surely, 2^18221661593 is an apocalyptic number.

It is an amenable number.

18221661593 is a deficient number, since it is larger than the sum of its proper divisors (1).

18221661593 is an equidigital number, since it uses as much as digits as its factorization.

18221661593 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 44.

The spelling of 18221661593 in words is "eighteen billion, two hundred twenty-one million, six hundred sixty-one thousand, five hundred ninety-three".