1641581 has 4 divisors (see below), whose sum is σ = 1728000. Its totient is φ = 1555164.

The previous prime is 1641559. The next prime is 1641583. The reversal of 1641581 is 1851461.

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: 1851461 = 661 ⋅2801.

It is a cyclic number.

It is not a de Polignac number, because 1641581 - 2¹⁰ = 1640557 is a prime.

It is a super-2 number, since 2×1641581² = 5389576359122, which contains 22 as substring.

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 1641581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1641583) 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, 43181 + ... + 43218.

It is an arithmetic number, because the mean of its divisors is an integer number (432000).

2^1641581 is an apocalyptic number.

It is an amenable number.

1641581 is a deficient number, since it is larger than the sum of its proper divisors (86419).

1641581 is an equidigital number, since it uses as much as digits as its factorization.

1641581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86418.

The product of its digits is 960, while the sum is 26.

The square root of 1641581 is about 1281.2419755846. The cubic root of 1641581 is about 117.9652535826.

It can be divided in two parts, 1641 and 581, that added together give a palindrome (2222).

The spelling of 1641581 in words is "one million, six hundred forty-one thousand, five hundred eighty-one".