640787633 has 2 divisors, whose sum is σ = 640787634. Its totient is φ = 640787632.

The previous prime is 640787627. The next prime is 640787657. The reversal of 640787633 is 336787046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 626400784 + 14386849 = 25028^2 + 3793^2 .

It is a cyclic number.

It is not a de Polignac number, because 640787633 - 2¹² = 640783537 is a prime.

It is not a weakly prime, because it can be changed into another prime (640787663) 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, 320393816 + 320393817.

It is an arithmetic number, because the mean of its divisors is an integer number (320393817).

Almost surely, 2^640787633 is an apocalyptic number.

It is an amenable number.

640787633 is a deficient number, since it is larger than the sum of its proper divisors (1).

640787633 is an equidigital number, since it uses as much as digits as its factorization.

640787633 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 508032, while the sum is 44.

The square root of 640787633 is about 25313.7834588194. The cubic root of 640787633 is about 862.1272527254.

The spelling of 640787633 in words is "six hundred forty million, seven hundred eighty-seven thousand, six hundred thirty-three".