66513947 has 4 divisors (see below), whose sum is σ = 67102680. Its totient is φ = 65925216.

The previous prime is 66513899. The next prime is 66513961. The reversal of 66513947 is 74931566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 74931566 = 2 ⋅37465783.

It is a cyclic number.

It is not a de Polignac number, because 66513947 - 2²² = 62319643 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66513047) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 294197 + ... + 294422.

It is an arithmetic number, because the mean of its divisors is an integer number (16775670).

Almost surely, 2^66513947 is an apocalyptic number.

66513947 is a deficient number, since it is larger than the sum of its proper divisors (588733).

66513947 is a wasteful number, since it uses less digits than its factorization.

66513947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588732.

The product of its digits is 136080, while the sum is 41.

The square root of 66513947 is about 8155.6083157543. The cubic root of 66513947 is about 405.1702723547.

The spelling of 66513947 in words is "sixty-six million, five hundred thirteen thousand, nine hundred forty-seven".