6639945 has 32 divisors (see below), whose sum is σ = 12120192. Its totient is φ = 3075072.

The previous prime is 6639943. The next prime is 6639989. The reversal of 6639945 is 5499366.

It is not a de Polignac number, because 6639945 - 2¹ = 6639943 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 6639897 and 6639906.

It is not an unprimeable number, because it can be changed into a prime (6639943) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2314 + ... + 4316.

It is an arithmetic number, because the mean of its divisors is an integer number (378756).

Almost surely, 2^6639945 is an apocalyptic number.

6639945 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

6639945 is a deficient number, since it is larger than the sum of its proper divisors (5480247).

6639945 is a wasteful number, since it uses less digits than its factorization.

6639945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2041.

The product of its digits is 174960, while the sum is 42.

The square root of 6639945 is about 2576.8090732532. The cubic root of 6639945 is about 187.9554085430.

The spelling of 6639945 in words is "six million, six hundred thirty-nine thousand, nine hundred forty-five".