6642635640 has 32 divisors (see below), whose sum is σ = 19927907280. Its totient is φ = 1771369472.

The previous prime is 6642635611. The next prime is 6642635653. The reversal of 6642635640 is 465362466.

It is a junction number, because it is equal to n+sod(n) for n = 6642635592 and 6642635601.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 27677529 + ... + 27677768.

Almost surely, 2^6642635640 is an apocalyptic number.

6642635640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

6642635640 is an abundant number, since it is smaller than the sum of its proper divisors (13285271640).

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

6642635640 is a wasteful number, since it uses less digits than its factorization.

6642635640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55355311 (or 55355307 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 42.

The square root of 6642635640 is about 81502.3658552315. The cubic root of 6642635640 is about 1879.8079289215.

It can be divided in two parts, 664263 and 5640, that added together give a triangular number (669903 = T₁₁₅₇).

The spelling of 6642635640 in words is "six billion, six hundred forty-two million, six hundred thirty-five thousand, six hundred forty".