66574721 has 2 divisors, whose sum is σ = 66574722. Its totient is φ = 66574720.

The previous prime is 66574709. The next prime is 66574723. The reversal of 66574721 is 12747566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54184321 + 12390400 = 7361^2 + 3520^2 .

It is a cyclic number.

It is not a de Polignac number, because 66574721 - 2¹⁸ = 66312577 is a prime.

Together with 66574723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66574723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33287360 + 33287361.

It is an arithmetic number, because the mean of its divisors is an integer number (33287361).

Almost surely, 2^66574721 is an apocalyptic number.

It is an amenable number.

66574721 is a deficient number, since it is larger than the sum of its proper divisors (1).

66574721 is an equidigital number, since it uses as much as digits as its factorization.

66574721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70560, while the sum is 38.

The square root of 66574721 is about 8159.3333673775. Note that the first 4 decimals coincide. The cubic root of 66574721 is about 405.2936365685.

The spelling of 66574721 in words is "sixty-six million, five hundred seventy-four thousand, seven hundred twenty-one".