645863780 has 24 divisors (see below), whose sum is σ = 1358772408. Its totient is φ = 257877248.

The previous prime is 645863767. The next prime is 645863797. The reversal of 645863780 is 87368546.

It can be written as a sum of positive squares in 4 ways, for example, as 602176 + 645261604 = 776^2 + 25402^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17849 + ... + 40128.

It is an arithmetic number, because the mean of its divisors is an integer number (56615517).

Almost surely, 2^645863780 is an apocalyptic number.

It is an amenable number.

645863780 is an abundant number, since it is smaller than the sum of its proper divisors (712908628).

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

645863780 is a wasteful number, since it uses less digits than its factorization.

645863780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58543 (or 58541 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 47.

The square root of 645863780 is about 25413.8501608867. The cubic root of 645863780 is about 864.3977810132.

The spelling of 645863780 in words is "six hundred forty-five million, eight hundred sixty-three thousand, seven hundred eighty".