66909888 has 70 divisors (see below), whose sum is σ = 198357236. Its totient is φ = 22301568.

The previous prime is 66909883. The next prime is 66909893. The reversal of 66909888 is 88890966.

It is an interprime number because it is at equal distance from previous prime (66909883) and next prime (66909893).

It is a super-2 number, since 2×66909888² = 8953866224345088, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (66909881) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1270 + ... + 11637.

Almost surely, 2^66909888 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 66909888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99178618).

66909888 is an abundant number, since it is smaller than the sum of its proper divisors (131447348).

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

66909888 is a wasteful number, since it uses less digits than its factorization.

66909888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12931 (or 12912 counting only the distinct ones).

The product of its (nonzero) digits is 1492992, while the sum is 54.

The square root of 66909888 is about 8179.8464533266. The cubic root of 66909888 is about 405.9726416729.

The spelling of 66909888 in words is "sixty-six million, nine hundred nine thousand, eight hundred eighty-eight".