66609998 has 48 divisors (see below), whose sum is σ = 126489600. Its totient is φ = 25747488.

The previous prime is 66609989. The next prime is 66610021. The reversal of 66609998 is 89990666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 110903 + ... + 111501.

It is an arithmetic number, because the mean of its divisors is an integer number (2635200).

Almost surely, 2^66609998 is an apocalyptic number.

66609998 is a deficient number, since it is larger than the sum of its proper divisors (59879602).

66609998 is a wasteful number, since it uses less digits than its factorization.

66609998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681 (or 668 counting only the distinct ones).

The product of its (nonzero) digits is 1259712, while the sum is 53.

The square root of 66609998 is about 8161.4948385697. The cubic root of 66609998 is about 405.3652103770.

The spelling of 66609998 in words is "sixty-six million, six hundred nine thousand, nine hundred ninety-eight".