66430721 has 12 divisors (see below), whose sum is σ = 77519088. Its totient is φ = 56761992.

The previous prime is 66430703. The next prime is 66430723. The reversal of 66430721 is 12703466.

It is not a de Polignac number, because 66430721 - 2¹⁰ = 66429697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66430723) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15050 + ... + 18956.

It is an arithmetic number, because the mean of its divisors is an integer number (6459924).

Almost surely, 2^66430721 is an apocalyptic number.

It is an amenable number.

66430721 is a deficient number, since it is larger than the sum of its proper divisors (11088367).

66430721 is a wasteful number, since it uses less digits than its factorization.

66430721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4268 (or 4261 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 29.

The square root of 66430721 is about 8150.5043402234. The cubic root of 66430721 is about 405.0012111939.

The spelling of 66430721 in words is "sixty-six million, four hundred thirty thousand, seven hundred twenty-one".