1680008921 has 4 divisors (see below), whose sum is σ = 1684328100. Its totient is φ = 1675689744.

The previous prime is 1680008917. The next prime is 1680008971. The reversal of 1680008921 is 1298000861.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 640849225 + 1039159696 = 25315^2 + 32236^2 .

It is a cyclic number.

It is not a de Polignac number, because 1680008921 - 2² = 1680008917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1680008971) 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, 2159006 + ... + 2159783.

It is an arithmetic number, because the mean of its divisors is an integer number (421082025).

Almost surely, 2^1680008921 is an apocalyptic number.

It is an amenable number.

1680008921 is a deficient number, since it is larger than the sum of its proper divisors (4319179).

1680008921 is an equidigital number, since it uses as much as digits as its factorization.

1680008921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4319178.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 1680008921 is about 40987.9118887508. The cubic root of 1680008921 is about 1188.7864947444.

The spelling of 1680008921 in words is "one billion, six hundred eighty million, eight thousand, nine hundred twenty-one".