6638244661 has 4 divisors (see below), whose sum is σ = 6690514432. Its totient is φ = 6585974892.

The previous prime is 6638244653. The next prime is 6638244689. The reversal of 6638244661 is 1664428366.

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: 1664428366 = 2 ⋅832214183.

It is a cyclic number.

It is not a de Polignac number, because 6638244661 - 2³ = 6638244653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6638244161) 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, 26134695 + ... + 26134948.

It is an arithmetic number, because the mean of its divisors is an integer number (1672628608).

Almost surely, 2^6638244661 is an apocalyptic number.

It is an amenable number.

6638244661 is a deficient number, since it is larger than the sum of its proper divisors (52269771).

6638244661 is a wasteful number, since it uses less digits than its factorization.

6638244661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52269770.

The product of its digits is 995328, while the sum is 46.

The square root of 6638244661 is about 81475.4236625990. The cubic root of 6638244661 is about 1879.3936347059.

The spelling of 6638244661 in words is "six billion, six hundred thirty-eight million, two hundred forty-four thousand, six hundred sixty-one".