66909920 has 96 divisors (see below), whose sum is σ = 197116416. Its totient is φ = 20851200.

The previous prime is 66909917. The next prime is 66909923. The reversal of 66909920 is 2990966.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66909917) and next prime (66909923).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66909923) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 9605 + ... + 15035.

It is an arithmetic number, because the mean of its divisors is an integer number (2053296).

Almost surely, 2^66909920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66909920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98558208).

66909920 is an abundant number, since it is smaller than the sum of its proper divisors (130206496).

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

66909920 is a wasteful number, since it uses less digits than its factorization.

66909920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5464 (or 5456 counting only the distinct ones).

The product of its (nonzero) digits is 52488, while the sum is 41.

The square root of 66909920 is about 8179.8484093533. The cubic root of 66909920 is about 405.9727063924.

The spelling of 66909920 in words is "sixty-six million, nine hundred nine thousand, nine hundred twenty".