66861247 has 4 divisors (see below), whose sum is σ = 70380280. Its totient is φ = 63342216.

The previous prime is 66861241. The next prime is 66861251. The reversal of 66861247 is 74216866.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66861247 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 (66861241) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1759488 + ... + 1759525.

It is an arithmetic number, because the mean of its divisors is an integer number (17595070).

Almost surely, 2^66861247 is an apocalyptic number.

66861247 is a deficient number, since it is larger than the sum of its proper divisors (3519033).

66861247 is a wasteful number, since it uses less digits than its factorization.

66861247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3519032.

The product of its digits is 96768, while the sum is 40.

The square root of 66861247 is about 8176.8726907052. The cubic root of 66861247 is about 405.8742421544.

The spelling of 66861247 in words is "sixty-six million, eight hundred sixty-one thousand, two hundred forty-seven".