18778890 has 64 divisors (see below), whose sum is σ = 48988800. Its totient is φ = 4579584.

The previous prime is 18778871. The next prime is 18778891. The reversal of 18778890 is 9887781.

18778890 = T₂₃₁ + T₂₃₂ + ... + T₄₉₉.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (18778891) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 69676 + ... + 69944.

It is an arithmetic number, because the mean of its divisors is an integer number (765450).

Almost surely, 2^18778890 is an apocalyptic number.

18778890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 18778890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24494400).

18778890 is an abundant number, since it is smaller than the sum of its proper divisors (30209910).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18778890 is a wasteful number, since it uses less digits than its factorization.

18778890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 471.

The product of its (nonzero) digits is 225792, while the sum is 48.

The square root of 18778890 is about 4333.4616647664. The cubic root of 18778890 is about 265.8010176375.

The spelling of 18778890 in words is "eighteen million, seven hundred seventy-eight thousand, eight hundred ninety".