18961406720887 has 4 divisors (see below), whose sum is σ = 19244412791416. Its totient is φ = 18678400650360.

The previous prime is 18961406720881. The next prime is 18961406720939. The reversal of 18961406720887 is 78802760416981.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18961406720887 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (67), and also a Moran number because the ratio is a prime number: 283006070461 = 18961406720887 / (1 + 8 + 9 + 6 + 1 + 4 + 0 + 6 + 7 + 2 + 0 + 8 + 8 + 7).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18961406720881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141503035164 + ... + 141503035297.

It is an arithmetic number, because the mean of its divisors is an integer number (4811103197854).

Almost surely, 2^{18961406720887} is an apocalyptic number.

18961406720887 is a deficient number, since it is larger than the sum of its proper divisors (283006070529).

18961406720887 is an equidigital number, since it uses as much as digits as its factorization.

18961406720887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283006070528.

The product of its (nonzero) digits is 65028096, while the sum is 67.

The spelling of 18961406720887 in words is "eighteen trillion, nine hundred sixty-one billion, four hundred six million, seven hundred twenty thousand, eight hundred eighty-seven".