645866056 has 48 divisors (see below), whose sum is σ = 1356320700. Its totient is φ = 288013440.

The previous prime is 645866029. The next prime is 645866083. The reversal of 645866056 is 650668546.

It is an interprime number because it is at equal distance from previous prime (645866029) and next prime (645866083).

It can be written as a sum of positive squares in 2 ways, for example, as 634536100 + 11329956 = 25190^2 + 3366^2 .

It is a junction number, because it is equal to n+sod(n) for n = 645865997 and 645866015.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45010 + ... + 57598.

Almost surely, 2^645866056 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 645866056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (678160350).

645866056 is an abundant number, since it is smaller than the sum of its proper divisors (710454644).

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

645866056 is a wasteful number, since it uses less digits than its factorization.

645866056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12670 (or 12655 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 46.

The square root of 645866056 is about 25413.8949395798. The cubic root of 645866056 is about 864.3987963805.

The spelling of 645866056 in words is "six hundred forty-five million, eight hundred sixty-six thousand, fifty-six".