645993792 has 140 divisors (see below), whose sum is σ = 1981420980. Its totient is φ = 207857664.

The previous prime is 645993739. The next prime is 645993793. The reversal of 645993792 is 297399546.

It can be written as a sum of positive squares in 2 ways, for example, as 342398016 + 303595776 = 18504^2 + 17424^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645993793) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 148188 + ... + 152484.

It is an arithmetic number, because the mean of its divisors is an integer number (14153007).

Almost surely, 2^645993792 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 645993792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (990710490).

645993792 is an abundant number, since it is smaller than the sum of its proper divisors (1335427188).

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

645993792 is a wasteful number, since it uses less digits than its factorization.

645993792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4350 (or 4331 counting only the distinct ones).

The product of its digits is 3674160, while the sum is 54.

The square root of 645993792 is about 25416.4079287377. The cubic root of 645993792 is about 864.4557780438.

The spelling of 645993792 in words is "six hundred forty-five million, nine hundred ninety-three thousand, seven hundred ninety-two".