66216816 has 60 divisors (see below), whose sum is σ = 193381968. Its totient is φ = 21111552.

The previous prime is 66216811. The next prime is 66216823. The reversal of 66216816 is 61861266.

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

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66216811) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6685 + ... + 13308.

Almost surely, 2^66216816 is an apocalyptic number.

It is an amenable number.

66216816 is an abundant number, since it is smaller than the sum of its proper divisors (127165152).

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

66216816 is a wasteful number, since it uses less digits than its factorization.

66216816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20030 (or 20021 counting only the distinct ones).

The product of its digits is 20736, while the sum is 36.

The square root of 66216816 is about 8137.3715658067. The cubic root of 66216816 is about 404.5660463915.

The spelling of 66216816 in words is "sixty-six million, two hundred sixteen thousand, eight hundred sixteen".