18987966761 has 2 divisors, whose sum is σ = 18987966762. Its totient is φ = 18987966760.

The previous prime is 18987966713. The next prime is 18987966769. The reversal of 18987966761 is 16766978981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14341499536 + 4646467225 = 119756^2 + 68165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18987966761 is a prime.

It is a super-2 number, since 2×18987966761² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18987966691 and 18987966700.

It is not a weakly prime, because it can be changed into another prime (18987966769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9493983380 + 9493983381.

It is an arithmetic number, because the mean of its divisors is an integer number (9493983381).

Almost surely, 2^18987966761 is an apocalyptic number.

It is an amenable number.

18987966761 is a deficient number, since it is larger than the sum of its proper divisors (1).

18987966761 is an equidigital number, since it uses as much as digits as its factorization.

18987966761 is an evil number, because the sum of its binary digits is even.

The product of its digits is 54867456, while the sum is 68.

The spelling of 18987966761 in words is "eighteen billion, nine hundred eighty-seven million, nine hundred sixty-six thousand, seven hundred sixty-one".