66217251 has 8 divisors (see below), whose sum is σ = 88327360. Its totient is φ = 44125992.

The previous prime is 66217241. The next prime is 66217279. The reversal of 66217251 is 15271266.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66217251 - 2⁹ = 66216739 is a prime.

It is a super-3 number, since 3×66217251³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66217201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10560 + ... + 15618.

It is an arithmetic number, because the mean of its divisors is an integer number (11040920).

Almost surely, 2^66217251 is an apocalyptic number.

66217251 is a deficient number, since it is larger than the sum of its proper divisors (22110109).

66217251 is a wasteful number, since it uses less digits than its factorization.

66217251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9425.

The product of its digits is 5040, while the sum is 30.

The square root of 66217251 is about 8137.3982942953. The cubic root of 66217251 is about 404.5669322986.

The spelling of 66217251 in words is "sixty-six million, two hundred seventeen thousand, two hundred fifty-one".