6643618425 has 54 divisors (see below), whose sum is σ = 12439543662. Its totient is φ = 3389147520.

The previous prime is 6643618417. The next prime is 6643618441. The reversal of 6643618425 is 5248163466.

6643618425 is a `hidden beast` number, since 6 + 6 + 4 + 3 + 618 + 4 + 25 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 2099105856 + 4544512569 = 45816^2 + 67413^2 .

It is not a de Polignac number, because 6643618425 - 2³ = 6643618417 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 91117 + ... + 146933.

Almost surely, 2^6643618425 is an apocalyptic number.

It is an amenable number.

6643618425 is a deficient number, since it is larger than the sum of its proper divisors (5795925237).

6643618425 is a wasteful number, since it uses less digits than its factorization.

6643618425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55879 (or 55848 counting only the distinct ones).

The product of its digits is 829440, while the sum is 45.

The square root of 6643618425 is about 81508.3948130498. The cubic root of 6643618425 is about 1879.9006308766.

The spelling of 6643618425 in words is "six billion, six hundred forty-three million, six hundred eighteen thousand, four hundred twenty-five".