1918201220 has 24 divisors (see below), whose sum is σ = 4338086424. Its totient is φ = 708258816.

The previous prime is 1918201199. The next prime is 1918201231. The reversal of 1918201220 is 221028191.

It can be written as a sum of positive squares in 4 ways, for example, as 57486724 + 1860714496 = 7582^2 + 43136^2 .

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 1918201220.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3688589 + ... + 3689108.

It is an arithmetic number, because the mean of its divisors is an integer number (180753601).

Almost surely, 2^1918201220 is an apocalyptic number.

1918201220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1918201220 is an abundant number, since it is smaller than the sum of its proper divisors (2419885204).

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

1918201220 is a wasteful number, since it uses less digits than its factorization.

1918201220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7377719 (or 7377717 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The square root of 1918201220 is about 43797.2741160908. The cubic root of 1918201220 is about 1242.5047402950.

The spelling of 1918201220 in words is "one billion, nine hundred eighteen million, two hundred one thousand, two hundred twenty".