6643605257 has 4 divisors (see below), whose sum is σ = 6857915136. Its totient is φ = 6429295380.

The previous prime is 6643605239. The next prime is 6643605313. The reversal of 6643605257 is 7525063466.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6643605257 - 2²⁴ = 6626828041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6643601257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107154893 + ... + 107154954.

It is an arithmetic number, because the mean of its divisors is an integer number (1714478784).

Almost surely, 2^6643605257 is an apocalyptic number.

It is an amenable number.

6643605257 is a deficient number, since it is larger than the sum of its proper divisors (214309879).

6643605257 is a wasteful number, since it uses less digits than its factorization.

6643605257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214309878.

The product of its (nonzero) digits is 907200, while the sum is 44.

The square root of 6643605257 is about 81508.3140360540. The cubic root of 6643605257 is about 1879.8993888552.

The spelling of 6643605257 in words is "six billion, six hundred forty-three million, six hundred five thousand, two hundred fifty-seven".