6639553 has 4 divisors (see below), whose sum is σ = 6708100. Its totient is φ = 6571008.

The previous prime is 6639547. The next prime is 6639593. The reversal of 6639553 is 3559366.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3559366 = 2 ⋅1779683.

It can be written as a sum of positive squares in 2 ways, for example, as 1495729 + 5143824 = 1223^2 + 2268^2 .

It is a cyclic number.

It is not a de Polignac number, because 6639553 - 2⁹ = 6639041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6639533) 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, 34128 + ... + 34321.

It is an arithmetic number, because the mean of its divisors is an integer number (1677025).

Almost surely, 2^6639553 is an apocalyptic number.

It is an amenable number.

6639553 is a deficient number, since it is larger than the sum of its proper divisors (68547).

6639553 is an equidigital number, since it uses as much as digits as its factorization.

6639553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68546.

The product of its digits is 72900, while the sum is 37.

The square root of 6639553 is about 2576.7330090640. The cubic root of 6639553 is about 187.9517097187.

The spelling of 6639553 in words is "six million, six hundred thirty-nine thousand, five hundred fifty-three".