641569 has 4 divisors (see below), whose sum is σ = 645120. Its totient is φ = 638020.

The previous prime is 641551. The next prime is 641579. The reversal of 641569 is 965146.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 641569 - 2⁷ = 641441 is a prime.

It is a super-2 number, since 2×641569² = 823221563522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 641569.

It is not an unprimeable number, because it can be changed into a prime (641519) 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, 1489 + ... + 1870.

It is an arithmetic number, because the mean of its divisors is an integer number (161280).

2⁶⁴¹⁵⁶⁹ is an apocalyptic number.

It is an amenable number.

641569 is a deficient number, since it is larger than the sum of its proper divisors (3551).

641569 is a wasteful number, since it uses less digits than its factorization.

641569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3550.

The product of its digits is 6480, while the sum is 31.

The square root of 641569 is about 800.9800247197. The cubic root of 641569 is about 86.2477532146.

The spelling of 641569 in words is "six hundred forty-one thousand, five hundred sixty-nine".