640400620 has 24 divisors (see below), whose sum is σ = 1391216400. Its totient is φ = 247326912.

The previous prime is 640400611. The next prime is 640400627. The reversal of 640400620 is 26004046.

It is a super-2 number, since 2×640400620² = 820225908192768800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640400591 and 640400600.

It is not an unprimeable number, because it can be changed into a prime (640400627) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 551490 + ... + 552649.

It is an arithmetic number, because the mean of its divisors is an integer number (57967350).

Almost surely, 2^640400620 is an apocalyptic number.

It is an amenable number.

640400620 is an abundant number, since it is smaller than the sum of its proper divisors (750815780).

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

640400620 is a wasteful number, since it uses less digits than its factorization.

640400620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1104177 (or 1104175 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 22.

The square root of 640400620 is about 25306.1379906141. The cubic root of 640400620 is about 861.9536530117.

Adding to 640400620 its reverse (26004046), we get a palindrome (666404666).

The spelling of 640400620 in words is "six hundred forty million, four hundred thousand, six hundred twenty".