1680538 has 4 divisors (see below), whose sum is σ = 2520810. Its totient is φ = 840268.

The previous prime is 1680529. The next prime is 1680551. The reversal of 1680538 is 8350861.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 8350861 = 19 ⋅439519.

It can be written as a sum of positive squares in only one way, i.e., 1580049 + 100489 = 1257^2 + 317^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420133 + ... + 420136.

2^1680538 is an apocalyptic number.

1680538 is a deficient number, since it is larger than the sum of its proper divisors (840272).

1680538 is an equidigital number, since it uses as much as digits as its factorization.

1680538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840271.

The product of its (nonzero) digits is 5760, while the sum is 31.

The square root of 1680538 is about 1296.3556610745. The cubic root of 1680538 is about 118.8911275025.

It can be divided in two parts, 1680 and 538, that multiplied together give a triangular number (903840 = T₁₃₄₄).

The spelling of 1680538 in words is "one million, six hundred eighty thousand, five hundred thirty-eight".