66990000 has 400 divisors, whose sum is σ = 278910720. Its totient is φ = 13440000.

The previous prime is 66989981. The next prime is 66990031. The reversal of 66990000 is 9966.

It is a tau number, because it is divible by the number of its divisors (400).

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 66990000.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 2309986 + ... + 2310014.

Almost surely, 2^66990000 is an apocalyptic number.

66990000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66990000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139455360).

66990000 is an abundant number, since it is smaller than the sum of its proper divisors (211920720).

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

66990000 is a wasteful number, since it uses less digits than its factorization.

66990000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 30.

The square root of 66990000 is about 8184.7419018562. The cubic root of 66990000 is about 406.1346023322.

Adding to 66990000 its reverse (9966), we get a palindrome (66999966).

The spelling of 66990000 in words is "sixty-six million, nine hundred ninety thousand".