6620664421 has 4 divisors (see below), whose sum is σ = 7566473632. Its totient is φ = 5674855212.

The previous prime is 6620664367. The next prime is 6620664487. The reversal of 6620664421 is 1244660266.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1244660266 = 2 ⋅622330133.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6620664421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6620662421) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 472904595 + ... + 472904608.

It is an arithmetic number, because the mean of its divisors is an integer number (1891618408).

Almost surely, 2^6620664421 is an apocalyptic number.

It is an amenable number.

6620664421 is a deficient number, since it is larger than the sum of its proper divisors (945809211).

6620664421 is an equidigital number, since it uses as much as digits as its factorization.

6620664421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 945809210.

The product of its (nonzero) digits is 82944, while the sum is 37.

The square root of 6620664421 is about 81367.4653716091. The cubic root of 6620664421 is about 1877.7330852232.

The spelling of 6620664421 in words is "six billion, six hundred twenty million, six hundred sixty-four thousand, four hundred twenty-one".