640623161 has 2 divisors, whose sum is σ = 640623162. Its totient is φ = 640623160.

The previous prime is 640623127. The next prime is 640623167. The reversal of 640623161 is 161326046.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 597313600 + 43309561 = 24440^2 + 6581^2 .

It is a cyclic number.

It is not a de Polignac number, because 640623161 - 2¹⁴ = 640606777 is a prime.

It is not a weakly prime, because it can be changed into another prime (640623167) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320311580 + 320311581.

It is an arithmetic number, because the mean of its divisors is an integer number (320311581).

Almost surely, 2^640623161 is an apocalyptic number.

It is an amenable number.

640623161 is a deficient number, since it is larger than the sum of its proper divisors (1).

640623161 is an equidigital number, since it uses as much as digits as its factorization.

640623161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 640623161 is about 25310.5345854251. The cubic root of 640623161 is about 862.0534852140.

The spelling of 640623161 in words is "six hundred forty million, six hundred twenty-three thousand, one hundred sixty-one".