641669887849 has 9 divisors (see below), whose sum is σ = 652778063287. Its totient is φ = 630747666544.

The previous prime is 641669887811. The next prime is 641669887913. The reversal of 641669887849 is 948788966146.

The square root of 641669887849 is 801043.

It is a perfect power (a square), and thus also a powerful number.

641669887849 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 618999165225 + 22670722624 = 786765^2 + 150568^2 .

It is not a de Polignac number, because 641669887849 - 2²⁷ = 641535670121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (641669887049) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 47254749 + ... + 47268325.

Almost surely, 2^641669887849 is an apocalyptic number.

641669887849 is the 801043-rd square number.

641669887849 is the 400522-nd centered octagonal number.

It is an amenable number.

641669887849 is a deficient number, since it is larger than the sum of its proper divisors (11108175438).

641669887849 is an frugal number, since it uses more digits than its factorization.

641669887849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27272 (or 13636 counting only the distinct ones).

The product of its digits is 1003290624, while the sum is 76.

The spelling of 641669887849 in words is "six hundred forty-one billion, six hundred sixty-nine million, eight hundred eighty-seven thousand, eight hundred forty-nine".