66216639 has 4 divisors (see below), whose sum is σ = 88288856. Its totient is φ = 44144424.

The previous prime is 66216637. The next prime is 66216641. The reversal of 66216639 is 93661266.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (66216637) and next prime (66216641).

It is not a de Polignac number, because 66216639 - 2¹ = 66216637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66216597 and 66216606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66216637) 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 3 ways as a sum of consecutive naturals, for example, 11036104 + ... + 11036109.

It is an arithmetic number, because the mean of its divisors is an integer number (22072214).

Almost surely, 2^66216639 is an apocalyptic number.

66216639 is a deficient number, since it is larger than the sum of its proper divisors (22072217).

66216639 is a wasteful number, since it uses less digits than its factorization.

66216639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22072216.

The product of its digits is 69984, while the sum is 39.

The square root of 66216639 is about 8137.3606900518. The cubic root of 66216639 is about 404.5656859179.

The spelling of 66216639 in words is "sixty-six million, two hundred sixteen thousand, six hundred thirty-nine".