640622993 has 2 divisors, whose sum is σ = 640622994. Its totient is φ = 640622992.

The previous prime is 640622971. The next prime is 640623001. The reversal of 640622993 is 399226046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 423001489 + 217621504 = 20567^2 + 14752^2 .

It is a cyclic number.

It is not a de Polignac number, because 640622993 - 2¹⁶ = 640557457 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640622993.

It is not a weakly prime, because it can be changed into another prime (640622923) 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, 320311496 + 320311497.

It is an arithmetic number, because the mean of its divisors is an integer number (320311497).

Almost surely, 2^640622993 is an apocalyptic number.

It is an amenable number.

640622993 is a deficient number, since it is larger than the sum of its proper divisors (1).

640622993 is an equidigital number, since it uses as much as digits as its factorization.

640622993 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 139968, while the sum is 41.

The square root of 640622993 is about 25310.5312666487. The cubic root of 640622993 is about 862.0534098577.

The spelling of 640622993 in words is "six hundred forty million, six hundred twenty-two thousand, nine hundred ninety-three".