645606401440 has 384 divisors, whose sum is σ = 2051841673728. Its totient is φ = 185389793280.

The previous prime is 645606401399. The next prime is 645606401441. The reversal of 645606401440 is 44104606546.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 645606401393 and 645606401402.

It is not an unprimeable number, because it can be changed into a prime (645606401441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 89205502 + ... + 89212738.

It is an arithmetic number, because the mean of its divisors is an integer number (5343337692).

Almost surely, 2^645606401440 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 645606401440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1025920836864).

645606401440 is an abundant number, since it is smaller than the sum of its proper divisors (1406235272288).

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

645606401440 is a wasteful number, since it uses less digits than its factorization.

645606401440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7840 (or 7832 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 40.

The spelling of 645606401440 in words is "six hundred forty-five billion, six hundred six million, four hundred one thousand, four hundred forty".