18661350663647 has 4 divisors (see below), whose sum is σ = 18661706461776. Its totient is φ = 18660994865520.

The previous prime is 18661350663611. The next prime is 18661350663653. The reversal of 18661350663647 is 74636605316681.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 18661350663647 - 2⁶ = 18661350663583 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18661350663647.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18661350663667) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 177820379 + ... + 177925292.

It is an arithmetic number, because the mean of its divisors is an integer number (4665426615444).

Almost surely, 2^{18661350663647} is an apocalyptic number.

18661350663647 is a deficient number, since it is larger than the sum of its proper divisors (355798129).

18661350663647 is an equidigital number, since it uses as much as digits as its factorization.

18661350663647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355798128.

The product of its (nonzero) digits is 78382080, while the sum is 62.

The spelling of 18661350663647 in words is "eighteen trillion, six hundred sixty-one billion, three hundred fifty million, six hundred sixty-three thousand, six hundred forty-seven".