645536663543640 has 64 divisors (see below), whose sum is σ = 2112665444328960. Its totient is φ = 156493736616320.

The previous prime is 645536663543621. The next prime is 645536663543657. The reversal of 645536663543640 is 46345366635546.

645536663543640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (66).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 244521462144 + ... + 244521464783.

It is an arithmetic number, because the mean of its divisors is an integer number (33010397567640).

Almost surely, 2^{645536663543640} is an apocalyptic number.

645536663543640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645536663543640 is an abundant number, since it is smaller than the sum of its proper divisors (1467128780785320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645536663543640 is a wasteful number, since it uses less digits than its factorization.

645536663543640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489042926952 (or 489042926948 counting only the distinct ones).

The product of its (nonzero) digits is 1679616000, while the sum is 66.

The spelling of 645536663543640 in words is "six hundred forty-five trillion, five hundred thirty-six billion, six hundred sixty-three million, five hundred forty-three thousand, six hundred forty".