640053521 has 2 divisors, whose sum is σ = 640053522. Its totient is φ = 640053520.

The previous prime is 640053517. The next prime is 640053611. The reversal of 640053521 is 125350046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 499299025 + 140754496 = 22345^2 + 11864^2 .

It is a cyclic number.

It is not a de Polignac number, because 640053521 - 2² = 640053517 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640053511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320026760 + 320026761.

It is an arithmetic number, because the mean of its divisors is an integer number (320026761).

Almost surely, 2^640053521 is an apocalyptic number.

It is an amenable number.

640053521 is a deficient number, since it is larger than the sum of its proper divisors (1).

640053521 is an equidigital number, since it uses as much as digits as its factorization.

640053521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 26.

The square root of 640053521 is about 25299.2790608744. The cubic root of 640053521 is about 861.7978977388.

The spelling of 640053521 in words is "six hundred forty million, fifty-three thousand, five hundred twenty-one".