66406663 has 4 divisors (see below), whose sum is σ = 67951048. Its totient is φ = 64862280.

The previous prime is 66406657. The next prime is 66406667. The reversal of 66406663 is 36660466.

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

It is a cyclic number.

It is not a de Polignac number, because 66406663 - 2²⁵ = 32852231 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 (66406667) 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, 772128 + ... + 772213.

It is an arithmetic number, because the mean of its divisors is an integer number (16987762).

Almost surely, 2^66406663 is an apocalyptic number.

66406663 is a deficient number, since it is larger than the sum of its proper divisors (1544385).

66406663 is a wasteful number, since it uses less digits than its factorization.

66406663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1544384.

The product of its (nonzero) digits is 93312, while the sum is 37.

The square root of 66406663 is about 8149.0283469871. The cubic root of 66406663 is about 404.9523146621.

The spelling of 66406663 in words is "sixty-six million, four hundred six thousand, six hundred sixty-three".