6644219991 has 32 divisors (see below), whose sum is σ = 9443796480. Its totient is φ = 4143283200.

The previous prime is 6644219971. The next prime is 6644219993. The reversal of 6644219991 is 1999124466.

It is not a de Polignac number, because 6644219991 - 2¹⁸ = 6643957847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6644219993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1808086 + ... + 1811756.

It is an arithmetic number, because the mean of its divisors is an integer number (295118640).

Almost surely, 2^6644219991 is an apocalyptic number.

6644219991 is a deficient number, since it is larger than the sum of its proper divisors (2799576489).

6644219991 is a wasteful number, since it uses less digits than its factorization.

6644219991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4087.

The product of its digits is 839808, while the sum is 51.

The square root of 6644219991 is about 81512.0849383697. The cubic root of 6644219991 is about 1879.9573695441.

The spelling of 6644219991 in words is "six billion, six hundred forty-four million, two hundred nineteen thousand, nine hundred ninety-one".