640656089 has 2 divisors, whose sum is σ = 640656090. Its totient is φ = 640656088.

The previous prime is 640656061. The next prime is 640656113. The reversal of 640656089 is 980656046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 452966089 + 187690000 = 21283^2 + 13700^2 .

It is a cyclic number.

It is not a de Polignac number, because 640656089 - 2⁸ = 640655833 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640656019) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320328044 + 320328045.

It is an arithmetic number, because the mean of its divisors is an integer number (320328045).

Almost surely, 2^640656089 is an apocalyptic number.

It is an amenable number.

640656089 is a deficient number, since it is larger than the sum of its proper divisors (1).

640656089 is an equidigital number, since it uses as much as digits as its factorization.

640656089 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 311040, while the sum is 44.

The square root of 640656089 is about 25311.1850572035. The cubic root of 640656089 is about 862.0682547970.

The spelling of 640656089 in words is "six hundred forty million, six hundred fifty-six thousand, eighty-nine".