218401820 has 192 divisors, whose sum is σ = 602112000. Its totient is φ = 66044160.

The previous prime is 218401819. The next prime is 218401829. The reversal of 218401820 is 28104812.

It is a Harshad number since it is a multiple of its sum of digits (26).

It is a self number, because there is not a number n which added to its sum of digits gives 218401820.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218401829) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2764541 + ... + 2764619.

It is an arithmetic number, because the mean of its divisors is an integer number (3136000).

Almost surely, 2^218401820 is an apocalyptic number.

218401820 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 218401820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (301056000).

218401820 is an abundant number, since it is smaller than the sum of its proper divisors (383710180).

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

218401820 is a wasteful number, since it uses less digits than its factorization.

218401820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 26.

The square root of 218401820 is about 14778.4241379113. The cubic root of 218401820 is about 602.2157150137.

The spelling of 218401820 in words is "two hundred eighteen million, four hundred one thousand, eight hundred twenty".