66978990 has 192 divisors, whose sum is σ = 207567360. Its totient is φ = 14826240.

The previous prime is 66978959. The next prime is 66979001. The reversal of 66978990 is 9987966.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 511225 + ... + 511355.

It is an arithmetic number, because the mean of its divisors is an integer number (1081080).

Almost surely, 2^66978990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66978990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103783680).

66978990 is an abundant number, since it is smaller than the sum of its proper divisors (140588370).

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

66978990 is a wasteful number, since it uses less digits than its factorization.

66978990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 196 counting only the distinct ones).

The product of its (nonzero) digits is 1469664, while the sum is 54.

The square root of 66978990 is about 8184.0692812317. The cubic root of 66978990 is about 406.1123513148.

The spelling of 66978990 in words is "sixty-six million, nine hundred seventy-eight thousand, nine hundred ninety".