6640399 has 8 divisors (see below), whose sum is σ = 7044192. Its totient is φ = 6246240.

The previous prime is 6640397. The next prime is 6640409. The reversal of 6640399 is 9930466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6640399 - 2¹ = 6640397 is a prime.

It is a Duffinian number.

6640399 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640393) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 964 + ... + 3769.

It is an arithmetic number, because the mean of its divisors is an integer number (880524).

Almost surely, 2^6640399 is an apocalyptic number.

6640399 is a deficient number, since it is larger than the sum of its proper divisors (403793).

6640399 is a wasteful number, since it uses less digits than its factorization.

6640399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4817.

The product of its (nonzero) digits is 34992, while the sum is 37.

The square root of 6640399 is about 2576.8971651969. The cubic root of 6640399 is about 187.9596922035.

The spelling of 6640399 in words is "six million, six hundred forty thousand, three hundred ninety-nine".