640656061 has 2 divisors, whose sum is σ = 640656062. Its totient is φ = 640656060.

The previous prime is 640656019. The next prime is 640656089. The reversal of 640656061 is 160656046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 505980036 + 134676025 = 22494^2 + 11605^2 .

It is a cyclic number.

It is not a de Polignac number, because 640656061 - 2⁹ = 640655549 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640656461) 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 as a sum of consecutive naturals, namely, 320328030 + 320328031.

It is an arithmetic number, because the mean of its divisors is an integer number (320328031).

Almost surely, 2^640656061 is an apocalyptic number.

It is an amenable number.

640656061 is a deficient number, since it is larger than the sum of its proper divisors (1).

640656061 is an equidigital number, since it uses as much as digits as its factorization.

640656061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 640656061 is about 25311.1845040883. The cubic root of 640656061 is about 862.0682422381.

The spelling of 640656061 in words is "six hundred forty million, six hundred fifty-six thousand, sixty-one".