6643503720 has 96 divisors (see below), whose sum is σ = 24675880320. Its totient is φ = 1518514560.

The previous prime is 6643503703. The next prime is 6643503751. The reversal of 6643503720 is 273053466.

6643503720 is a `hidden beast` number, since 6 + 643 + 5 + 0 + 3 + 7 + 2 + 0 = 666.

It is a super-2 number, since 2×6643503720² = 88272283355307676800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1315636 + ... + 1320675.

It is an arithmetic number, because the mean of its divisors is an integer number (257040420).

Almost surely, 2^6643503720 is an apocalyptic number.

6643503720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6643503720 is an abundant number, since it is smaller than the sum of its proper divisors (18032376600).

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

6643503720 is a wasteful number, since it uses less digits than its factorization.

6643503720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2636335 (or 2636328 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 36.

The square root of 6643503720 is about 81507.6911708337. The cubic root of 6643503720 is about 1879.8898117100.

It can be divided in two parts, 664 and 3503720, that added together give a square (3504384 = 1872²).

The spelling of 6643503720 in words is "six billion, six hundred forty-three million, five hundred three thousand, seven hundred twenty".