20001640 has 16 divisors (see below), whose sum is σ = 45003780. Its totient is φ = 8000640.

The previous prime is 20001613. The next prime is 20001659. The reversal of 20001640 is 4610002.

It can be written as a sum of positive squares in 2 ways, for example, as 19589476 + 412164 = 4426^2 + 642^2 .

20001640 is a modest number, since divided by 1640 gives 200 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20001640.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 249981 + ... + 250060.

Almost surely, 2^20001640 is an apocalyptic number.

20001640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20001640 is an abundant number, since it is smaller than the sum of its proper divisors (25002140).

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

20001640 is a wasteful number, since it uses less digits than its factorization.

20001640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500052 (or 500048 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 20001640 is about 4472.3193088151. The cubic root of 20001640 is about 271.4491808649.

Adding to 20001640 its reverse (4610002), we get a palindrome (24611642).

The spelling of 20001640 in words is "twenty million, one thousand, six hundred forty".