640365643 has 2 divisors, whose sum is σ = 640365644. Its totient is φ = 640365642.

The previous prime is 640365631. The next prime is 640365727. The reversal of 640365643 is 346563046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640365643 - 2¹⁷ = 640234571 is a prime.

It is not a weakly prime, because it can be changed into another prime (640365613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320182821 + 320182822.

It is an arithmetic number, because the mean of its divisors is an integer number (320182822).

Almost surely, 2^640365643 is an apocalyptic number.

640365643 is a deficient number, since it is larger than the sum of its proper divisors (1).

640365643 is an equidigital number, since it uses as much as digits as its factorization.

640365643 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 155520, while the sum is 37.

The square root of 640365643 is about 25305.4469037794. The cubic root of 640365643 is about 861.9379601777.

The spelling of 640365643 in words is "six hundred forty million, three hundred sixty-five thousand, six hundred forty-three".