66645216 has 144 divisors (see below), whose sum is σ = 209729520. Its totient is φ = 19906560.

The previous prime is 66645199. The next prime is 66645233. The reversal of 66645216 is 61254666.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66645199) and next prime (66645233).

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 345216 + ... + 345408.

It is an arithmetic number, because the mean of its divisors is an integer number (1456455).

Almost surely, 2^66645216 is an apocalyptic number.

66645216 is a gapful number since it is divisible by the number (66) 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 66645216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104864760).

66645216 is an abundant number, since it is smaller than the sum of its proper divisors (143084304).

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

66645216 is a wasteful number, since it uses less digits than its factorization.

66645216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329 (or 318 counting only the distinct ones).

The product of its digits is 51840, while the sum is 36.

The square root of 66645216 is about 8163.6521238965. The cubic root of 66645216 is about 405.4366392772.

The spelling of 66645216 in words is "sixty-six million, six hundred forty-five thousand, two hundred sixteen".