1641 has 4 divisors (see below), whose sum is σ = 2192. Its totient is φ = 1092.

The previous prime is 1637. The next prime is 1657. The reversal of 1641 is 1461.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1461 = 3 ⋅487.

It is not a de Polignac number, because 1641 - 2^{2} = 1637 is a prime.

It is an Ulam number.

It is a D-number.

It is the 41-st Hogben number.

It is a Duffinian number.

1641 is a lucky number.

It is a plaindrome in base 6, base 9 and base 16.

It is a nialpdrome in base 13 and base 14.

It is a zygodrome in base 6.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 1641.

It is not an unprimeable number, because it can be changed into a prime (1601) by changing a digit.

It is a nontrivial repunit in base 40.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 271 + ... + 276.

It is an arithmetic number, because the mean of its divisors is an integer number (548).

It is an amenable number.

1641 is a deficient number, since it is larger than the sum of its proper divisors (551).

1641 is an equidigital number, since it uses as much as digits as its factorization.

1641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550.

The product of its digits is 24, while the sum is 12.

The square root of 1641 is about 40.5092582011. The cubic root of 1641 is about 11.7951334907.

Adding to 1641 its sum of digits (12), we get a triangular number (1653 = T_{57}).

It can be divided in two parts, 16 and 41, that multiplied together give a palindrome (656).

The spelling of 1641 in words is "one thousand, six hundred forty-one".

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