1680621 has 4 divisors (see below), whose sum is σ = 2240832. Its totient is φ = 1120412.

The previous prime is 1680617. The next prime is 1680643. The reversal of 1680621 is 1260861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1680621 - 2² = 1680617 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 1680591 and 1680600.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1680121) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 280101 + ... + 280106.

It is an arithmetic number, because the mean of its divisors is an integer number (560208).

2^1680621 is an apocalyptic number.

It is an amenable number.

1680621 is a deficient number, since it is larger than the sum of its proper divisors (560211).

1680621 is an equidigital number, since it uses as much as digits as its factorization.

1680621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560210.

The product of its (nonzero) digits is 576, while the sum is 24.

The square root of 1680621 is about 1296.3876734989. The cubic root of 1680621 is about 118.8930847728.

The spelling of 1680621 in words is "one million, six hundred eighty thousand, six hundred twenty-one".