645724440420 has 24 divisors (see below), whose sum is σ = 1808028433344. Its totient is φ = 172193184096.

The previous prime is 645724440409. The next prime is 645724440437. The reversal of 645724440420 is 24044427546.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5381036944 + ... + 5381037063.

It is an arithmetic number, because the mean of its divisors is an integer number (75334518056).

Almost surely, 2^645724440420 is an apocalyptic number.

645724440420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645724440420 is an abundant number, since it is smaller than the sum of its proper divisors (1162303992924).

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

645724440420 is a wasteful number, since it uses less digits than its factorization.

645724440420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10762074019 (or 10762074017 counting only the distinct ones).

The product of its (nonzero) digits is 860160, while the sum is 42.

Adding to 645724440420 its reverse (24044427546), we get a palindrome (669768867966).

The spelling of 645724440420 in words is "six hundred forty-five billion, seven hundred twenty-four million, four hundred forty thousand, four hundred twenty".