665640001 has 8 divisors (see below), whose sum is σ = 723421160. Its totient is φ = 608798592.

The previous prime is 665639993. The next prime is 665640013. The reversal of 665640001 is 100046566.

665640001 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Cunningham number, because it is equal to 25800²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 1 + 665640000 = 1^2 + 25800^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 665640001 - 2³ = 665639993 is a prime.

It is a super-2 number, since 2×665640001² = 886153221862560002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665646001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 233460 + ... + 236293.

It is an arithmetic number, because the mean of its divisors is an integer number (90427645).

Almost surely, 2^665640001 is an apocalyptic number.

It is an amenable number.

665640001 is a deficient number, since it is larger than the sum of its proper divisors (57781159).

665640001 is a wasteful number, since it uses less digits than its factorization.

665640001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469875.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 665640001 is about 25800.0000193798. Note that the first 4 decimals coincide. The cubic root of 665640001 is about 873.1317968063.

Adding to 665640001 its reverse (100046566), we get a palindrome (765686567).

The spelling of 665640001 in words is "six hundred sixty-five million, six hundred forty thousand, one".