645820436 has 6 divisors (see below), whose sum is σ = 1130185770. Its totient is φ = 322910216.

The previous prime is 645820421. The next prime is 645820453. The reversal of 645820436 is 634028546.

It can be written as a sum of positive squares in only one way, i.e., 355322500 + 290497936 = 18850^2 + 17044^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 645820436.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80727551 + ... + 80727558.

It is an arithmetic number, because the mean of its divisors is an integer number (188364295).

Almost surely, 2^645820436 is an apocalyptic number.

It is an amenable number.

645820436 is a deficient number, since it is larger than the sum of its proper divisors (484365334).

645820436 is a wasteful number, since it uses less digits than its factorization.

645820436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161455113 (or 161455111 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 38.

The square root of 645820436 is about 25412.9973832289. The cubic root of 645820436 is about 864.3784439658.

The spelling of 645820436 in words is "six hundred forty-five million, eight hundred twenty thousand, four hundred thirty-six".