66659988 has 24 divisors (see below), whose sum is σ = 155675520. Its totient is φ = 22200640.

The previous prime is 66659987. The next prime is 66659993. The reversal of 66659988 is 88995666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66659981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20968 + ... + 23936.

It is an arithmetic number, because the mean of its divisors is an integer number (6486480).

Almost surely, 2^66659988 is an apocalyptic number.

It is an amenable number.

66659988 is an abundant number, since it is smaller than the sum of its proper divisors (89015532).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66659988 is a wasteful number, since it uses less digits than its factorization.

66659988 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4847 (or 4845 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 57.

The square root of 66659988 is about 8164.5568158964. The cubic root of 66659988 is about 405.4665922528.

It can be divided in two parts, 6665 and 9988, that added together give a triangular number (16653 = T₁₈₂).

The spelling of 66659988 in words is "sixty-six million, six hundred fifty-nine thousand, nine hundred eighty-eight".