645606720 has 224 divisors, whose sum is σ = 2484973440. Its totient is φ = 156487680.

The previous prime is 645606697. The next prime is 645606721. The reversal of 645606720 is 27606546.

645606720 is a `hidden beast` number, since 6 + 45 + 606 + 7 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645606721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 91644 + ... + 98436.

Almost surely, 2^645606720 is an apocalyptic number.

645606720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645606720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1242486720).

645606720 is an abundant number, since it is smaller than the sum of its proper divisors (1839366720).

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

645606720 is a wasteful number, since it uses less digits than its factorization.

645606720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6830 (or 6814 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 36.

The square root of 645606720 is about 25408.7921790864. The cubic root of 645606720 is about 864.2830862501.

The spelling of 645606720 in words is "six hundred forty-five million, six hundred six thousand, seven hundred twenty".