645642120 has 32 divisors (see below), whose sum is σ = 1936926720. Its totient is φ = 172171200.

The previous prime is 645642113. The next prime is 645642139. The reversal of 645642120 is 21246546.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2690056 + ... + 2690295.

It is an arithmetic number, because the mean of its divisors is an integer number (60528960).

Almost surely, 2^645642120 is an apocalyptic number.

645642120 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

645642120 is an abundant number, since it is smaller than the sum of its proper divisors (1291284600).

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

645642120 is a wasteful number, since it uses less digits than its factorization.

645642120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5380365 (or 5380361 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 30.

The square root of 645642120 is about 25409.4887788007. The cubic root of 645642120 is about 864.2988827927.

Adding to 645642120 its reverse (21246546), we get a palindrome (666888666).

The spelling of 645642120 in words is "six hundred forty-five million, six hundred forty-two thousand, one hundred twenty".