640030728 has 16 divisors (see below), whose sum is σ = 1600076880. Its totient is φ = 213343568.

The previous prime is 640030717. The next prime is 640030763. The reversal of 640030728 is 827030046.

It is a junction number, because it is equal to n+sod(n) for n = 640030695 and 640030704.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13333950 + ... + 13333997.

It is an arithmetic number, because the mean of its divisors is an integer number (100004805).

Almost surely, 2^640030728 is an apocalyptic number.

It is an amenable number.

640030728 is an abundant number, since it is smaller than the sum of its proper divisors (960046152).

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

640030728 is a wasteful number, since it uses less digits than its factorization.

640030728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26667956 (or 26667952 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 30.

The square root of 640030728 is about 25298.8285894822. The cubic root of 640030728 is about 861.7876677648.

It can be divided in two parts, 6400 and 30728, that added together give a triangular number (37128 = T₂₇₂).

The spelling of 640030728 in words is "six hundred forty million, thirty thousand, seven hundred twenty-eight".