18961518977251 has 2 divisors, whose sum is σ = 18961518977252. Its totient is φ = 18961518977250.

The previous prime is 18961518977249. The next prime is 18961518977309. The reversal of 18961518977251 is 15277981516981.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18961518977251 - 2¹ = 18961518977249 is a prime.

Together with 18961518977249, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18961518977231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9480759488625 + 9480759488626.

It is an arithmetic number, because the mean of its divisors is an integer number (9480759488626).

Almost surely, 2^{18961518977251} is an apocalyptic number.

18961518977251 is a deficient number, since it is larger than the sum of its proper divisors (1).

18961518977251 is an equidigital number, since it uses as much as digits as its factorization.

18961518977251 is an evil number, because the sum of its binary digits is even.

The product of its digits is 76204800, while the sum is 70.

The spelling of 18961518977251 in words is "eighteen trillion, nine hundred sixty-one billion, five hundred eighteen million, nine hundred seventy-seven thousand, two hundred fifty-one".