640555031 has 2 divisors, whose sum is σ = 640555032. Its totient is φ = 640555030.

The previous prime is 640555009. The next prime is 640555061. The reversal of 640555031 is 130555046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640555031 - 2²² = 636360727 is a prime.

It is a super-2 number, since 2×640555031² = 820621495478821922, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 640554985 and 640555003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640555001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320277515 + 320277516.

It is an arithmetic number, because the mean of its divisors is an integer number (320277516).

Almost surely, 2^640555031 is an apocalyptic number.

640555031 is a deficient number, since it is larger than the sum of its proper divisors (1).

640555031 is an equidigital number, since it uses as much as digits as its factorization.

640555031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9000, while the sum is 29.

The square root of 640555031 is about 25309.1886673595. The cubic root of 640555031 is about 862.0229244571.

The spelling of 640555031 in words is "six hundred forty million, five hundred fifty-five thousand, thirty-one".