666101998 has 4 divisors (see below), whose sum is σ = 999153000. Its totient is φ = 333050998.

The previous prime is 666101987. The next prime is 666101999. The reversal of 666101998 is 899101666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 899101666 = 2 ⋅449550833.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666101999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166525498 + ... + 166525501.

It is an arithmetic number, because the mean of its divisors is an integer number (249788250).

Almost surely, 2^666101998 is an apocalyptic number.

666101998 is a deficient number, since it is larger than the sum of its proper divisors (333051002).

666101998 is a wasteful number, since it uses less digits than its factorization.

666101998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333051001.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 666101998 is about 25808.9518965804. The cubic root of 666101998 is about 873.3337533100. Note that the first 3 decimals are identical.

The spelling of 666101998 in words is "six hundred sixty-six million, one hundred one thousand, nine hundred ninety-eight".