1681945 has 8 divisors (see below), whose sum is σ = 2065536. Its totient is φ = 1314096.

The previous prime is 1681931. The next prime is 1681957. The reversal of 1681945 is 5491861.

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 1681945 - 2⁷ = 1681817 is a prime.

It is a super-3 number, since 3×1681945³ = 14274359333411950875, which contains 333 as substring.

It is an Ulam number.

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 1681945.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3697 + ... + 4126.

It is an arithmetic number, because the mean of its divisors is an integer number (258192).

2^1681945 is an apocalyptic number.

It is an amenable number.

1681945 is a deficient number, since it is larger than the sum of its proper divisors (383591).

1681945 is an equidigital number, since it uses as much as digits as its factorization.

1681945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7871.

The product of its digits is 8640, while the sum is 34.

The square root of 1681945 is about 1296.8982226836. The cubic root of 1681945 is about 118.9242980614.

The spelling of 1681945 in words is "one million, six hundred eighty-one thousand, nine hundred forty-five".