1681989 has 16 divisors (see below), whose sum is σ = 2334720. Its totient is φ = 1076400.

The previous prime is 1681973. The next prime is 1681991. The reversal of 1681989 is 9891861.

It is not a de Polignac number, because 1681989 - 2⁴ = 1681973 is a prime.

It is a super-2 number, since 2×1681989² = 5658173992242, which contains 22 as substring.

It is a Curzon number.

1681989 is a lucky number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 1681989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681289) 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, 11064 + ... + 11214.

It is an arithmetic number, because the mean of its divisors is an integer number (145920).

2^1681989 is an apocalyptic number.

It is an amenable number.

1681989 is a deficient number, since it is larger than the sum of its proper divisors (652731).

1681989 is a wasteful number, since it uses less digits than its factorization.

1681989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280.

The product of its digits is 31104, while the sum is 42.

The square root of 1681989 is about 1296.9151861244. The cubic root of 1681989 is about 118.9253350798.

The spelling of 1681989 in words is "one million, six hundred eighty-one thousand, nine hundred eighty-nine".