645606540 has 72 divisors (see below), whose sum is σ = 1971391968. Its totient is φ = 171014400.

The previous prime is 645606539. The next prime is 645606557. The reversal of 645606540 is 45606546.

It is a happy number.

645606540 is a `hidden beast` number, since 6 + 4 + 5 + 606 + 5 + 40 = 666.

645606540 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is a junction number, because it is equal to n+sod(n) for n = 645606495 and 645606504.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15304 + ... + 39056.

It is an arithmetic number, because the mean of its divisors is an integer number (27380444).

Almost surely, 2^645606540 is an apocalyptic number.

645606540 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 645606540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (985695984).

645606540 is an abundant number, since it is smaller than the sum of its proper divisors (1325785428).

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

645606540 is a wasteful number, since it uses less digits than its factorization.

645606540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23919 (or 23914 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The square root of 645606540 is about 25408.7886370051. The cubic root of 645606540 is about 864.2830059272.

The spelling of 645606540 in words is "six hundred forty-five million, six hundred six thousand, five hundred forty".