645402120 has 256 divisors, whose sum is σ = 2199674880. Its totient is φ = 150144000.

The previous prime is 645402119. The next prime is 645402139. The reversal of 645402120 is 21204546.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6265989 + ... + 6266091.

It is an arithmetic number, because the mean of its divisors is an integer number (8592480).

Almost surely, 2^645402120 is an apocalyptic number.

645402120 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 645402120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1099837440).

645402120 is an abundant number, since it is smaller than the sum of its proper divisors (1554272760).

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

645402120 is a wasteful number, since it uses less digits than its factorization.

645402120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276 (or 272 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 645402120 is about 25404.7656946487. The cubic root of 645402120 is about 864.1917762739.

Adding to 645402120 its reverse (21204546), we get a palindrome (666606666).

The spelling of 645402120 in words is "six hundred forty-five million, four hundred two thousand, one hundred twenty".