6643975 has 12 divisors (see below), whose sum is σ = 8872696. Its totient is φ = 4906080.

The previous prime is 6643969. The next prime is 6643981. The reversal of 6643975 is 5793466.

It is an interprime number because it is at equal distance from previous prime (6643969) and next prime (6643981).

It is not a de Polignac number, because 6643975 - 2¹⁷ = 6512903 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9897 + ... + 10546.

Almost surely, 2^6643975 is an apocalyptic number.

6643975 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

6643975 is a deficient number, since it is larger than the sum of its proper divisors (2228721).

6643975 is a wasteful number, since it uses less digits than its factorization.

6643975 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20466 (or 20461 counting only the distinct ones).

The product of its digits is 136080, while the sum is 40.

The square root of 6643975 is about 2577.5909295309. The cubic root of 6643975 is about 187.9934262829.

The spelling of 6643975 in words is "six million, six hundred forty-three thousand, nine hundred seventy-five".