6643745 has 4 divisors (see below), whose sum is σ = 7972500. Its totient is φ = 5314992.

The previous prime is 6643739. The next prime is 6643781. The reversal of 6643745 is 5473466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5473466 = 2 ⋅2736733.

It can be written as a sum of positive squares in 2 ways, for example, as 1982464 + 4661281 = 1408^2 + 2159^2 .

It is a cyclic number.

It is not a de Polignac number, because 6643745 - 2⁴ = 6643729 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 664370 + ... + 664379.

It is an arithmetic number, because the mean of its divisors is an integer number (1993125).

Almost surely, 2^6643745 is an apocalyptic number.

It is an amenable number.

6643745 is a deficient number, since it is larger than the sum of its proper divisors (1328755).

6643745 is a wasteful number, since it uses less digits than its factorization.

6643745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1328754.

The product of its digits is 60480, while the sum is 35.

The square root of 6643745 is about 2577.5463138419. The cubic root of 6643745 is about 187.9912569497.

The spelling of 6643745 in words is "six million, six hundred forty-three thousand, seven hundred forty-five".