640550042 has 12 divisors (see below), whose sum is σ = 1056113898. Its totient is φ = 291159000.

The previous prime is 640550041. The next prime is 640550047. The reversal of 640550042 is 240055046.

It can be written as a sum of positive squares in only one way, i.e., 341917081 + 298632961 = 18491^2 + 17281^2 .

It is a junction number, because it is equal to n+sod(n) for n = 640549993 and 640550020.

It is not an unprimeable number, because it can be changed into a prime (640550041) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1323209 + ... + 1323692.

Almost surely, 2^640550042 is an apocalyptic number.

640550042 is a deficient number, since it is larger than the sum of its proper divisors (415563856).

640550042 is a wasteful number, since it uses less digits than its factorization.

640550042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2646925 (or 2646914 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 26.

The square root of 640550042 is about 25309.0901061259. The cubic root of 640550042 is about 862.0206864795.

The spelling of 640550042 in words is "six hundred forty million, five hundred fifty thousand, forty-two".