20040640 has 28 divisors (see below), whose sum is σ = 47722536. Its totient is φ = 8016128.

The previous prime is 20040619. The next prime is 20040667. The reversal of 20040640 is 4604002.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

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, 30994 + ... + 31633.

Almost surely, 2^20040640 is an apocalyptic number.

20040640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20040640 is an abundant number, since it is smaller than the sum of its proper divisors (27681896).

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

20040640 is an equidigital number, since it uses as much as digits as its factorization.

20040640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62644 (or 62634 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 20040640 is about 4476.6773392774. The cubic root of 20040640 is about 271.6254938209.

Adding to 20040640 its reverse (4604002), we get a palindrome (24644642).

The spelling of 20040640 in words is "twenty million, forty thousand, six hundred forty".