66864481 has 4 divisors (see below), whose sum is σ = 68495364. Its totient is φ = 65233600.

The previous prime is 66864443. The next prime is 66864487. The reversal of 66864481 is 18446866.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2608225 + 64256256 = 1615^2 + 8016^2 .

It is a cyclic number.

It is not a de Polignac number, because 66864481 - 2¹⁷ = 66733409 is a prime.

It is a super-2 number, since 2×66864481² = 8941717638798722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66864487) 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, 815380 + ... + 815461.

It is an arithmetic number, because the mean of its divisors is an integer number (17123841).

Almost surely, 2^66864481 is an apocalyptic number.

It is an amenable number.

66864481 is a deficient number, since it is larger than the sum of its proper divisors (1630883).

66864481 is a wasteful number, since it uses less digits than its factorization.

66864481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1630882.

The product of its digits is 221184, while the sum is 43.

The square root of 66864481 is about 8177.0704411788. The cubic root of 66864481 is about 405.8807859357.

The spelling of 66864481 in words is "sixty-six million, eight hundred sixty-four thousand, four hundred eighty-one".