640722120 has 64 divisors (see below), whose sum is σ = 1927800000. Its totient is φ = 170358528.

The previous prime is 640722107. The next prime is 640722127. The reversal of 640722120 is 21227046.

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

It is not an unprimeable number, because it can be changed into a prime (640722127) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 34231 + ... + 49529.

It is an arithmetic number, because the mean of its divisors is an integer number (30121875).

Almost surely, 2^640722120 is an apocalyptic number.

640722120 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 640722120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (963900000).

640722120 is an abundant number, since it is smaller than the sum of its proper divisors (1287077880).

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

640722120 is a wasteful number, since it uses less digits than its factorization.

640722120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15662 (or 15658 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 640722120 is about 25312.4894074052. The cubic root of 640722120 is about 862.0978709329.

Adding to 640722120 its reverse (21227046), we get a palindrome (661949166).

The spelling of 640722120 in words is "six hundred forty million, seven hundred twenty-two thousand, one hundred twenty".