645434500621 has 2 divisors, whose sum is σ = 645434500622. Its totient is φ = 645434500620.

The previous prime is 645434500561. The next prime is 645434500631. The reversal of 645434500621 is 126005434546.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 603239589225 + 42194911396 = 776685^2 + 205414^2 .

It is a cyclic number.

It is not a de Polignac number, because 645434500621 - 2¹³ = 645434492429 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (645434500631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322717250310 + 322717250311.

It is an arithmetic number, because the mean of its divisors is an integer number (322717250311).

Almost surely, 2^645434500621 is an apocalyptic number.

It is an amenable number.

645434500621 is a deficient number, since it is larger than the sum of its proper divisors (1).

645434500621 is an equidigital number, since it uses as much as digits as its factorization.

645434500621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 345600, while the sum is 40.

The spelling of 645434500621 in words is "six hundred forty-five billion, four hundred thirty-four million, five hundred thousand, six hundred twenty-one".