66572781 has 16 divisors (see below), whose sum is σ = 97070400. Its totient is φ = 40248320.

The previous prime is 66572773. The next prime is 66572783. The reversal of 66572781 is 18727566.

It is a cyclic number.

It is not a de Polignac number, because 66572781 - 2³ = 66572773 is a prime.

It is a super-2 number, since 2×66572781² = 8863870340147922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66572783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12571 + ... + 17063.

It is an arithmetic number, because the mean of its divisors is an integer number (6066900).

Almost surely, 2^66572781 is an apocalyptic number.

It is an amenable number.

66572781 is a deficient number, since it is larger than the sum of its proper divisors (30497619).

66572781 is a wasteful number, since it uses less digits than its factorization.

66572781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4956.

The product of its digits is 141120, while the sum is 42.

The square root of 66572781 is about 8159.2144842503. The cubic root of 66572781 is about 405.2896997524.

The spelling of 66572781 in words is "sixty-six million, five hundred seventy-two thousand, seven hundred eighty-one".