1681581 has 8 divisors (see below), whose sum is σ = 2445984. Its totient is φ = 1019120.

The previous prime is 1681579. The next prime is 1681591. The reversal of 1681581 is 1851861.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1681581 - 2¹ = 1681579 is a prime.

It is a super-2 number, since 2×1681581² = 5655429319122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25446 + ... + 25511.

It is an arithmetic number, because the mean of its divisors is an integer number (305748).

2^1681581 is an apocalyptic number.

1681581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1681581 is a deficient number, since it is larger than the sum of its proper divisors (764403).

1681581 is a wasteful number, since it uses less digits than its factorization.

1681581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50971.

The product of its digits is 1920, while the sum is 30.

The square root of 1681581 is about 1296.7578802537. The cubic root of 1681581 is about 118.9157183977.

The spelling of 1681581 in words is "one million, six hundred eighty-one thousand, five hundred eighty-one".