640236340 has 12 divisors (see below), whose sum is σ = 1344496356. Its totient is φ = 256094528.

The previous prime is 640236287. The next prime is 640236347. The reversal of 640236340 is 43632046.

It can be written as a sum of positive squares in 2 ways, for example, as 349465636 + 290770704 = 18694^2 + 17052^2 .

It is a junction number, because it is equal to n+sod(n) for n = 640236299 and 640236308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640236347) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16005889 + ... + 16005928.

It is an arithmetic number, because the mean of its divisors is an integer number (112041363).

Almost surely, 2^640236340 is an apocalyptic number.

It is an amenable number.

640236340 is an abundant number, since it is smaller than the sum of its proper divisors (704260016).

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

640236340 is a wasteful number, since it uses less digits than its factorization.

640236340 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32011826 (or 32011824 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 28.

The square root of 640236340 is about 25302.8919295799. The cubic root of 640236340 is about 861.8799419358.

Adding to 640236340 its reverse (43632046), we get a palindrome (683868386).

The spelling of 640236340 in words is "six hundred forty million, two hundred thirty-six thousand, three hundred forty".