1680000021 has 20 divisors (see below), whose sum is σ = 2868149152. Its totient is φ = 959999688.

The previous prime is 1680000013. The next prime is 1680000029. The reversal of 1680000021 is 1200000861.

It is an interprime number because it is at equal distance from previous prime (1680000013) and next prime (1680000029).

It is not a de Polignac number, because 1680000021 - 2³ = 1680000013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1679999949 and 1680000003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1680000029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1480915 + ... + 1482048.

Almost surely, 2^1680000021 is an apocalyptic number.

It is an amenable number.

1680000021 is a deficient number, since it is larger than the sum of its proper divisors (1188149131).

1680000021 is an equidigital number, since it uses as much as digits as its factorization.

1680000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2962982 (or 2962973 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 1680000021 is about 40987.8033200122. The cubic root of 1680000021 is about 1188.7843955059.

Adding to 1680000021 its reverse (1200000861), we get a palindrome (2880000882).

The spelling of 1680000021 in words is "one billion, six hundred eighty million, twenty-one", and thus it is an aban number.