6640334021 has 4 divisors (see below), whose sum is σ = 6739443552. Its totient is φ = 6541224492.

The previous prime is 6640334017. The next prime is 6640334053. The reversal of 6640334021 is 1204330466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6640334021 - 2² = 6640334017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640334221) 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, 49554665 + ... + 49554798.

It is an arithmetic number, because the mean of its divisors is an integer number (1684860888).

Almost surely, 2^6640334021 is an apocalyptic number.

It is an amenable number.

6640334021 is a deficient number, since it is larger than the sum of its proper divisors (99109531).

6640334021 is an equidigital number, since it uses as much as digits as its factorization.

6640334021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99109530.

The product of its (nonzero) digits is 10368, while the sum is 29.

The square root of 6640334021 is about 81488.2446798310. The cubic root of 6640334021 is about 1879.5907911423.

Adding to 6640334021 its reverse (1204330466), we get a palindrome (7844664487).

The spelling of 6640334021 in words is "six billion, six hundred forty million, three hundred thirty-four thousand, twenty-one".