66814809 has 4 divisors (see below), whose sum is σ = 89086416. Its totient is φ = 44543204.

The previous prime is 66814807. The next prime is 66814817. The reversal of 66814809 is 90841866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66814809 - 2¹ = 66814807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66814801) 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, 11135799 + ... + 11135804.

It is an arithmetic number, because the mean of its divisors is an integer number (22271604).

Almost surely, 2^66814809 is an apocalyptic number.

It is an amenable number.

66814809 is a deficient number, since it is larger than the sum of its proper divisors (22271607).

66814809 is a wasteful number, since it uses less digits than its factorization.

66814809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22271606.

The product of its (nonzero) digits is 82944, while the sum is 42.

The square root of 66814809 is about 8174.0326033115. The cubic root of 66814809 is about 405.7802547094.

The spelling of 66814809 in words is "sixty-six million, eight hundred fourteen thousand, eight hundred nine".