18778449938 has 8 divisors (see below), whose sum is σ = 28928963532. Its totient is φ = 9135462096.

The previous prime is 18778449931. The next prime is 18778449971. The reversal of 18778449938 is 83994487781.

It can be written as a sum of positive squares in 2 ways, for example, as 14904258889 + 3874191049 = 122083^2 + 62243^2 .

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 (18778449931) 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, 126881345 + ... + 126881492.

Almost surely, 2^18778449938 is an apocalyptic number.

18778449938 is a deficient number, since it is larger than the sum of its proper divisors (10150513594).

18778449938 is a wasteful number, since it uses less digits than its factorization.

18778449938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 253762876.

The product of its digits is 97542144, while the sum is 68.

The spelling of 18778449938 in words is "eighteen billion, seven hundred seventy-eight million, four hundred forty-nine thousand, nine hundred thirty-eight".