1989664188777 has 20 divisors (see below), whose sum is σ = 3068092293376. Its totient is φ = 1283654313720.

The previous prime is 1989664188767. The next prime is 1989664188781. The reversal of 1989664188777 is 7778814669891.

1989664188777 is a `hidden beast` number, since 198 + 9 + 6 + 6 + 418 + 8 + 7 + 7 + 7 = 666.

It is not a de Polignac number, because 1989664188777 - 2⁴ = 1989664188761 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1989664188696 and 1989664188705.

It is not an unprimeable number, because it can be changed into a prime (1989664188767) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 396187093 + ... + 396192114.

Almost surely, 2^{1989664188777} is an apocalyptic number.

It is an amenable number.

1989664188777 is a deficient number, since it is larger than the sum of its proper divisors (1078428104599).

1989664188777 is an equidigital number, since it uses as much as digits as its factorization.

1989664188777 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 792379250 (or 792379241 counting only the distinct ones).

The product of its digits is 2048385024, while the sum is 81.

The spelling of 1989664188777 in words is "one trillion, nine hundred eighty-nine billion, six hundred sixty-four million, one hundred eighty-eight thousand, seven hundred seventy-seven".