18947249666 has 8 divisors (see below), whose sum is σ = 30092690700. Its totient is φ = 8916352768.

The previous prime is 18947249639. The next prime is 18947249669. The reversal of 18947249666 is 66694274981.

It can be written as a sum of positive squares in 2 ways, for example, as 18912025441 + 35224225 = 137521^2 + 5935^2 .

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

It is a super-2 number, since 2×18947249666² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18947249599 and 18947249608.

It is not an unprimeable number, because it can be changed into a prime (18947249669) 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, 278635991 + ... + 278636058.

Almost surely, 2^18947249666 is an apocalyptic number.

18947249666 is a deficient number, since it is larger than the sum of its proper divisors (11145441034).

18947249666 is a wasteful number, since it uses less digits than its factorization.

18947249666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 557272068.

The product of its digits is 31352832, while the sum is 62.

The spelling of 18947249666 in words is "eighteen billion, nine hundred forty-seven million, two hundred forty-nine thousand, six hundred sixty-six".