640121165465321 has 2 divisors, whose sum is σ = 640121165465322. Its totient is φ = 640121165465320.

The previous prime is 640121165465269. The next prime is 640121165465407. The reversal of 640121165465321 is 123564561121046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 353763020170921 + 286358145294400 = 18808589^2 + 16922120^2 .

It is a cyclic number.

It is not a de Polignac number, because 640121165465321 - 2²² = 640121161271017 is a prime.

It is not a weakly prime, because it can be changed into another prime (640121161465321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320060582732660 + 320060582732661.

It is an arithmetic number, because the mean of its divisors is an integer number (320060582732661).

Almost surely, 2^{640121165465321} is an apocalyptic number.

It is an amenable number.

640121165465321 is a deficient number, since it is larger than the sum of its proper divisors (1).

640121165465321 is an equidigital number, since it uses as much as digits as its factorization.

640121165465321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1036800, while the sum is 47.

The spelling of 640121165465321 in words is "six hundred forty trillion, one hundred twenty-one billion, one hundred sixty-five million, four hundred sixty-five thousand, three hundred twenty-one".