66216861 has 12 divisors (see below), whose sum is σ = 97871488. Its totient is φ = 43117704.

The previous prime is 66216851. The next prime is 66216863. The reversal of 66216861 is 16861266.

It is not a de Polignac number, because 66216861 - 2¹⁵ = 66184093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66216863) 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, 85165 + ... + 85938.

Almost surely, 2^66216861 is an apocalyptic number.

It is an amenable number.

66216861 is a deficient number, since it is larger than the sum of its proper divisors (31654627).

66216861 is a wasteful number, since it uses less digits than its factorization.

66216861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171152 (or 171149 counting only the distinct ones).

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

The square root of 66216861 is about 8137.3743308269. The cubic root of 66216861 is about 404.5661380373.

The spelling of 66216861 in words is "sixty-six million, two hundred sixteen thousand, eight hundred sixty-one".