1666778422558 has 4 divisors (see below), whose sum is σ = 2500167633840. Its totient is φ = 833389211278.

The previous prime is 1666778422553. The next prime is 1666778422577. The reversal of 1666778422558 is 8552248776661.

It is a happy number.

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

It is a junction number, because it is equal to n+sod(n) for n = 1666778422493 and 1666778422502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666778422553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 416694605638 + ... + 416694605641.

It is an arithmetic number, because the mean of its divisors is an integer number (625041908460).

Almost surely, 2^{1666778422558} is an apocalyptic number.

1666778422558 is a deficient number, since it is larger than the sum of its proper divisors (833389211282).

1666778422558 is an equidigital number, since it uses as much as digits as its factorization.

1666778422558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 833389211281.

The product of its digits is 270950400, while the sum is 67.

The spelling of 1666778422558 in words is "one trillion, six hundred sixty-six billion, seven hundred seventy-eight million, four hundred twenty-two thousand, five hundred fifty-eight".