18756220666 has 8 divisors (see below), whose sum is σ = 29789291700. Its totient is φ = 8826456768.

The previous prime is 18756220663. The next prime is 18756220669. The reversal of 18756220666 is 66602265781.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (18756220663) and next prime (18756220669).

It can be written as a sum of positive squares in 2 ways, for example, as 18706306441 + 49914225 = 136771^2 + 7065^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (18756220661) 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, 275826741 + ... + 275826808.

Almost surely, 2^18756220666 is an apocalyptic number.

18756220666 is a deficient number, since it is larger than the sum of its proper divisors (11033071034).

18756220666 is a wasteful number, since it uses less digits than its factorization.

18756220666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 551653568.

The product of its (nonzero) digits is 1451520, while the sum is 49.

The spelling of 18756220666 in words is "eighteen billion, seven hundred fifty-six million, two hundred twenty thousand, six hundred sixty-six".