646555728 has 80 divisors (see below), whose sum is σ = 2055729536. Its totient is φ = 170519040.

The previous prime is 646555709. The next prime is 646555729. The reversal of 646555728 is 827555646.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646555729) 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, 69643 + ... + 78378.

Almost surely, 2^646555728 is an apocalyptic number.

It is an amenable number.

646555728 is an abundant number, since it is smaller than the sum of its proper divisors (1409173808).

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

646555728 is a wasteful number, since it uses less digits than its factorization.

646555728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148052 (or 148046 counting only the distinct ones).

The product of its digits is 2016000, while the sum is 48.

The square root of 646555728 is about 25427.4601169680. The cubic root of 646555728 is about 864.7063625143.

The spelling of 646555728 in words is "six hundred forty-six million, five hundred fifty-five thousand, seven hundred twenty-eight".