18779220 has 162 divisors, whose sum is σ = 63863982. Its totient is φ = 4465152.

The previous prime is 18779219. The next prime is 18779221. The reversal of 18779220 is 2297781.

It is an interprime number because it is at equal distance from previous prime (18779219) and next prime (18779221).

It can be written as a sum of positive squares in 3 ways, for example, as 6290064 + 12489156 = 2508^2 + 3534^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18779221) 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 53 ways as a sum of consecutive naturals, for example, 988371 + ... + 988389.

Almost surely, 2^18779220 is an apocalyptic number.

18779220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18779220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31931991).

18779220 is an abundant number, since it is smaller than the sum of its proper divisors (45084762).

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

18779220 is a wasteful number, since it uses less digits than its factorization.

18779220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 18779220 is about 4333.4997403946. The cubic root of 18779220 is about 265.8025745954.

Adding to 18779220 its sum of digits (36), we get a triangular number (18779256 = T₆₁₂₈).

The spelling of 18779220 in words is "eighteen million, seven hundred seventy-nine thousand, two hundred twenty".