640436501 has 2 divisors, whose sum is σ = 640436502. Its totient is φ = 640436500.

The previous prime is 640436497. The next prime is 640436513. The reversal of 640436501 is 105634046.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 544102276 + 96334225 = 23326^2 + 9815^2 .

It is a cyclic number.

It is not a de Polignac number, because 640436501 - 2² = 640436497 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640436701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320218250 + 320218251.

It is an arithmetic number, because the mean of its divisors is an integer number (320218251).

Almost surely, 2^640436501 is an apocalyptic number.

It is an amenable number.

640436501 is a deficient number, since it is larger than the sum of its proper divisors (1).

640436501 is an equidigital number, since it uses as much as digits as its factorization.

640436501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 640436501 is about 25306.8469193616. The cubic root of 640436501 is about 861.9697508419.

The spelling of 640436501 in words is "six hundred forty million, four hundred thirty-six thousand, five hundred one".