665724001 has 2 divisors, whose sum is σ = 665724002. Its totient is φ = 665724000.

The previous prime is 665723999. The next prime is 665724023. The reversal of 665724001 is 100427566.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 665691601 + 32400 = 25801^2 + 180^2 .

It is a cyclic number.

It is not a de Polignac number, because 665724001 - 2¹ = 665723999 is a prime.

Together with 665723999, it forms a pair of twin primes.

It is equal to p_34568131 and since 665724001 and 34568131 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (665724061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332862000 + 332862001.

It is an arithmetic number, because the mean of its divisors is an integer number (332862001).

Almost surely, 2^665724001 is an apocalyptic number.

It is an amenable number.

665724001 is a deficient number, since it is larger than the sum of its proper divisors (1).

665724001 is an equidigital number, since it uses as much as digits as its factorization.

665724001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 665724001 is about 25801.6278750004. The cubic root of 665724001 is about 873.1685233582.

The spelling of 665724001 in words is "six hundred sixty-five million, seven hundred twenty-four thousand, one".