6663551 has 4 divisors (see below), whose sum is σ = 6706152. Its totient is φ = 6620952.

The previous prime is 6663539. The next prime is 6663557. The reversal of 6663551 is 1553666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6663551 - 2⁶ = 6663487 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6663557) 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, 21065 + ... + 21378.

It is an arithmetic number, because the mean of its divisors is an integer number (1676538).

Almost surely, 2^6663551 is an apocalyptic number.

6663551 is a deficient number, since it is larger than the sum of its proper divisors (42601).

6663551 is a wasteful number, since it uses less digits than its factorization.

6663551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42600.

The product of its digits is 16200, while the sum is 32.

The square root of 6663551 is about 2581.3854807060. The cubic root of 6663551 is about 188.1778816616.

The spelling of 6663551 in words is "six million, six hundred sixty-three thousand, five hundred fifty-one".