645454204220 has 72 divisors (see below), whose sum is σ = 1579096898064. Its totient is φ = 220969534464.

The previous prime is 645454204217. The next prime is 645454204237. The reversal of 645454204220 is 22402454546.

It is a super-2 number, since 2×645454204220² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 170219 + ... + 1148861.

It is an arithmetic number, because the mean of its divisors is an integer number (21931901362).

Almost surely, 2^645454204220 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645454204220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (789548449032).

645454204220 is an abundant number, since it is smaller than the sum of its proper divisors (933642693844).

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

645454204220 is a wasteful number, since it uses less digits than its factorization.

645454204220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 979339 (or 979330 counting only the distinct ones).

The product of its (nonzero) digits is 307200, while the sum is 38.

Adding to 645454204220 its reverse (22402454546), we get a palindrome (667856658766).

The spelling of 645454204220 in words is "six hundred forty-five billion, four hundred fifty-four million, two hundred four thousand, two hundred twenty".