218129920 has 80 divisors (see below), whose sum is σ = 527622480. Its totient is φ = 86482944.

The previous prime is 218129917. The next prime is 218129939. The reversal of 218129920 is 29921812.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 355534 + ... + 356146.

It is an arithmetic number, because the mean of its divisors is an integer number (6595281).

Almost surely, 2^218129920 is an apocalyptic number.

218129920 is a gapful number since it is divisible by the number (20) 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 218129920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (263811240).

218129920 is an abundant number, since it is smaller than the sum of its proper divisors (309492560).

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

218129920 is an equidigital number, since it uses as much as digits as its factorization.

218129920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 775 (or 759 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 218129920 is about 14769.2220512795. Note that the first 3 decimals coincide. The cubic root of 218129920 is about 601.9657011470.

The spelling of 218129920 in words is "two hundred eighteen million, one hundred twenty-nine thousand, nine hundred twenty".