66511491 has 4 divisors (see below), whose sum is σ = 88681992. Its totient is φ = 44340992.

The previous prime is 66511477. The next prime is 66511493. The reversal of 66511491 is 19411566.

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 66511491 - 2⁷ = 66511363 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66511493) 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, 11085246 + ... + 11085251.

It is an arithmetic number, because the mean of its divisors is an integer number (22170498).

Almost surely, 2^66511491 is an apocalyptic number.

66511491 is a deficient number, since it is larger than the sum of its proper divisors (22170501).

66511491 is a wasteful number, since it uses less digits than its factorization.

66511491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22170500.

The product of its digits is 6480, while the sum is 33.

The square root of 66511491 is about 8155.4577431313. The cubic root of 66511491 is about 405.1652853784.

The spelling of 66511491 in words is "sixty-six million, five hundred eleven thousand, four hundred ninety-one".