641965 has 4 divisors (see below), whose sum is σ = 770364. Its totient is φ = 513568.

The previous prime is 641959. The next prime is 641969. The reversal of 641965 is 569146.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 569146 = 2 ⋅284573.

It can be written as a sum of positive squares in 2 ways, for example, as 405769 + 236196 = 637^2 + 486^2 .

It is a cyclic number.

It is not a de Polignac number, because 641965 - 2⁹ = 641453 is a prime.

It is a super-2 number, since 2×641965² = 824238122450, 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 congruent number.

It is not an unprimeable number, because it can be changed into a prime (641969) 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, 64192 + ... + 64201.

It is an arithmetic number, because the mean of its divisors is an integer number (192591).

2⁶⁴¹⁹⁶⁵ is an apocalyptic number.

It is an amenable number.

641965 is a deficient number, since it is larger than the sum of its proper divisors (128399).

641965 is a wasteful number, since it uses less digits than its factorization.

641965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128398.

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

The square root of 641965 is about 801.2271837625. The cubic root of 641965 is about 86.2654946608.

The spelling of 641965 in words is "six hundred forty-one thousand, nine hundred sixty-five".