1641681 has 16 divisors (see below), whose sum is σ = 2493120. Its totient is φ = 1067040.

The previous prime is 1641659. The next prime is 1641709. The reversal of 1641681 is 1861461.

1641681 = 99² + 100² + ... + 180².

It is not a de Polignac number, because 1641681 - 2⁶ = 1641617 is a prime.

It is a super-2 number, since 2×1641681² = 5390233011522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1641631) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 366 + ... + 1848.

It is an arithmetic number, because the mean of its divisors is an integer number (155820).

2^1641681 is an apocalyptic number.

It is an amenable number.

1641681 is a deficient number, since it is larger than the sum of its proper divisors (851439).

1641681 is a wasteful number, since it uses less digits than its factorization.

1641681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1533 (or 1527 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 1641681 is about 1281.2809996250. The cubic root of 1641681 is about 117.9676488925.

The spelling of 1641681 in words is "one million, six hundred forty-one thousand, six hundred eighty-one".