645189820220 has 48 divisors (see below), whose sum is σ = 1478584654848. Its totient is φ = 234532983360.

The previous prime is 645189820169. The next prime is 645189820229. The reversal of 645189820220 is 22028981546.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645189820229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 127229 + ... + 1143051.

It is an arithmetic number, because the mean of its divisors is an integer number (30803846976).

Almost surely, 2^645189820220 is an apocalyptic number.

It is an amenable number.

645189820220 is an abundant number, since it is smaller than the sum of its proper divisors (833394834628).

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

645189820220 is a wasteful number, since it uses less digits than its factorization.

645189820220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1018730 (or 1018728 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 47.

The spelling of 645189820220 in words is "six hundred forty-five billion, one hundred eighty-nine million, eight hundred twenty thousand, two hundred twenty".