6651091638 has 48 divisors (see below), whose sum is σ = 14495800176. Its totient is φ = 2203975680.

The previous prime is 6651091591. The next prime is 6651091639. The reversal of 6651091638 is 8361901566.

6651091638 is a `hidden beast` number, since 6 + 6 + 5 + 1 + 0 + 9 + 1 + 638 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 6651091593 and 6651091602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6651091639) by changing a digit.

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, 2964145 + ... + 2966387.

It is an arithmetic number, because the mean of its divisors is an integer number (301995837).

Almost surely, 2^6651091638 is an apocalyptic number.

6651091638 is an abundant number, since it is smaller than the sum of its proper divisors (7844708538).

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

6651091638 is a wasteful number, since it uses less digits than its factorization.

6651091638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3149 (or 3146 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The square root of 6651091638 is about 81554.2251388608. The cubic root of 6651091638 is about 1880.6052485760.

The spelling of 6651091638 in words is "six billion, six hundred fifty-one million, ninety-one thousand, six hundred thirty-eight".