641091665 has 8 divisors (see below), whose sum is σ = 772049448. Its totient is φ = 511047040.

The previous prime is 641091631. The next prime is 641091667. The reversal of 641091665 is 566190146.

It can be written as a sum of positive squares in 4 ways, for example, as 277655569 + 363436096 = 16663^2 + 19064^2 .

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

It is not a de Polignac number, because 641091665 - 2¹⁶ = 641026129 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641091667) 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, 226742 + ... + 229551.

It is an arithmetic number, because the mean of its divisors is an integer number (96506181).

Almost surely, 2^641091665 is an apocalyptic number.

It is an amenable number.

641091665 is a deficient number, since it is larger than the sum of its proper divisors (130957783).

641091665 is a wasteful number, since it uses less digits than its factorization.

641091665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 456579.

The product of its (nonzero) digits is 38880, while the sum is 38.

The square root of 641091665 is about 25319.7880125407. The cubic root of 641091665 is about 862.2635812142.

The spelling of 641091665 in words is "six hundred forty-one million, ninety-one thousand, six hundred sixty-five".