2666638657 has 4 divisors (see below), whose sum is σ = 2806988080. Its totient is φ = 2526289236.

The previous prime is 2666638643. The next prime is 2666638687. The reversal of 2666638657 is 7568366662.

It is a happy number.

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 2666638657 - 2⁷ = 2666638529 is a prime.

It is a super-2 number, since 2×2666638657² = 14221923454013527298, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2666638598 and 2666638607.

It is not an unprimeable number, because it can be changed into a prime (2666638627) 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, 70174683 + ... + 70174720.

It is an arithmetic number, because the mean of its divisors is an integer number (701747020).

Almost surely, 2^2666638657 is an apocalyptic number.

It is an amenable number.

2666638657 is a deficient number, since it is larger than the sum of its proper divisors (140349423).

2666638657 is a wasteful number, since it uses less digits than its factorization.

2666638657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140349422.

The product of its digits is 13063680, while the sum is 55.

The square root of 2666638657 is about 51639.5067462887. The cubic root of 2666638657 is about 1386.7176934797.

The spelling of 2666638657 in words is "two billion, six hundred sixty-six million, six hundred thirty-eight thousand, six hundred fifty-seven".