18171205440551 has 2 divisors, whose sum is σ = 18171205440552. Its totient is φ = 18171205440550.

The previous prime is 18171205440463. The next prime is 18171205440571. The reversal of 18171205440551 is 15504450217181.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18171205440551 - 2³⁰ = 18170131698727 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18171205440571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9085602720275 + 9085602720276.

It is an arithmetic number, because the mean of its divisors is an integer number (9085602720276).

Almost surely, 2^{18171205440551} is an apocalyptic number.

18171205440551 is a deficient number, since it is larger than the sum of its proper divisors (1).

18171205440551 is an equidigital number, since it uses as much as digits as its factorization.

18171205440551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 224000, while the sum is 44.

The spelling of 18171205440551 in words is "eighteen trillion, one hundred seventy-one billion, two hundred five million, four hundred forty thousand, five hundred fifty-one".