6640819 has 4 divisors (see below), whose sum is σ = 6724960. Its totient is φ = 6556680.

The previous prime is 6640817. The next prime is 6640831. The reversal of 6640819 is 9180466.

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 6640819 - 2¹ = 6640817 is a prime.

It is a super-2 number, since 2×6640819² = 88200953981522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6640817) 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, 41952 + ... + 42109.

It is an arithmetic number, because the mean of its divisors is an integer number (1681240).

Almost surely, 2^6640819 is an apocalyptic number.

6640819 is a deficient number, since it is larger than the sum of its proper divisors (84141).

6640819 is an equidigital number, since it uses as much as digits as its factorization.

6640819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84140.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 6640819 is about 2576.9786572651. The cubic root of 6640819 is about 187.9636548874.

The spelling of 6640819 in words is "six million, six hundred forty thousand, eight hundred nineteen".