640121165465407 has 2 divisors, whose sum is σ = 640121165465408. Its totient is φ = 640121165465406.

The previous prime is 640121165465321. The next prime is 640121165465437. The reversal of 640121165465407 is 704564561121046.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640121165465407 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640121165465437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320060582732703 + 320060582732704.

It is an arithmetic number, because the mean of its divisors is an integer number (320060582732704).

Almost surely, 2^{640121165465407} is an apocalyptic number.

640121165465407 is a deficient number, since it is larger than the sum of its proper divisors (1).

640121165465407 is an equidigital number, since it uses as much as digits as its factorization.

640121165465407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4838400, while the sum is 52.

The spelling of 640121165465407 in words is "six hundred forty trillion, one hundred twenty-one billion, one hundred sixty-five million, four hundred sixty-five thousand, four hundred seven".