665613401 has 2 divisors, whose sum is σ = 665613402. Its totient is φ = 665613400.

The previous prime is 665613391. The next prime is 665613413. The reversal of 665613401 is 104316566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 547326025 + 118287376 = 23395^2 + 10876^2 .

It is a cyclic number.

It is not a de Polignac number, because 665613401 - 2⁶ = 665613337 is a prime.

It is not a weakly prime, because it can be changed into another prime (665613101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332806700 + 332806701.

It is an arithmetic number, because the mean of its divisors is an integer number (332806701).

Almost surely, 2^665613401 is an apocalyptic number.

It is an amenable number.

665613401 is a deficient number, since it is larger than the sum of its proper divisors (1).

665613401 is an equidigital number, since it uses as much as digits as its factorization.

665613401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 665613401 is about 25799.4845103541. The cubic root of 665613401 is about 873.1201660875.

Adding to 665613401 its reverse (104316566), we get a palindrome (769929967).

The spelling of 665613401 in words is "six hundred sixty-five million, six hundred thirteen thousand, four hundred one".