66689998 has 4 divisors (see below), whose sum is σ = 100035000. Its totient is φ = 33344998.

The previous prime is 66689969. The next prime is 66689999. The reversal of 66689998 is 89998666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 89998666 = 2 ⋅44999333.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66689999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16672498 + ... + 16672501.

It is an arithmetic number, because the mean of its divisors is an integer number (25008750).

Almost surely, 2^66689998 is an apocalyptic number.

66689998 is a deficient number, since it is larger than the sum of its proper divisors (33345002).

66689998 is a wasteful number, since it uses less digits than its factorization.

66689998 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33345001.

The product of its digits is 10077696, while the sum is 61.

The square root of 66689998 is about 8166.3944308367. The cubic root of 66689998 is about 405.5274294819.

The spelling of 66689998 in words is "sixty-six million, six hundred eighty-nine thousand, nine hundred ninety-eight".