1688400020 has 24 divisors (see below), whose sum is σ = 3558832200. Its totient is φ = 672847232.

The previous prime is 1688400019. The next prime is 1688400023. The reversal of 1688400020 is 200048861.

It can be written as a sum of positive squares in 4 ways, for example, as 18696976 + 1669703044 = 4324^2 + 40862^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1688400023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 151535 + ... + 162294.

It is an arithmetic number, because the mean of its divisors is an integer number (148284675).

Almost surely, 2^1688400020 is an apocalyptic number.

1688400020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1688400020 is an abundant number, since it is smaller than the sum of its proper divisors (1870432180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1688400020 is a wasteful number, since it uses less digits than its factorization.

1688400020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314107 (or 314105 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 1688400020 is about 41090.1450472008. The cubic root of 1688400020 is about 1190.7624095353.

Adding to 1688400020 its reverse (200048861), we get a palindrome (1888448881).

The spelling of 1688400020 in words is "one billion, six hundred eighty-eight million, four hundred thousand, twenty".