641965591 has 4 divisors (see below), whose sum is σ = 642541432. Its totient is φ = 641389752.

The previous prime is 641965589. The next prime is 641965603. The reversal of 641965591 is 195569146.

It is a happy number.

641965591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195569146 = 2 ⋅97784573.

It is a cyclic number.

It is not a de Polignac number, because 641965591 - 2¹ = 641965589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (641965531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286245 + ... + 288478.

It is an arithmetic number, because the mean of its divisors is an integer number (160635358).

Almost surely, 2^641965591 is an apocalyptic number.

641965591 is a deficient number, since it is larger than the sum of its proper divisors (575841).

641965591 is a wasteful number, since it uses less digits than its factorization.

641965591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 575840.

The product of its digits is 291600, while the sum is 46.

The square root of 641965591 is about 25337.0399020880. The cubic root of 641965591 is about 862.6552113307.

It can be divided in two parts, 6419 and 65591, that added together give a triangular number (72010 = T₃₇₉).

The spelling of 641965591 in words is "six hundred forty-one million, nine hundred sixty-five thousand, five hundred ninety-one".