209961220 has 96 divisors (see below), whose sum is σ = 545190912. Its totient is φ = 66275328.

The previous prime is 209961211. The next prime is 209961263. The reversal of 209961220 is 22169902.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 110922 + ... + 112798.

It is an arithmetic number, because the mean of its divisors is an integer number (5679072).

Almost surely, 2^209961220 is an apocalyptic number.

209961220 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 209961220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (272595456).

209961220 is an abundant number, since it is smaller than the sum of its proper divisors (335229692).

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

209961220 is a wasteful number, since it uses less digits than its factorization.

209961220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1957 (or 1955 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 209961220 is about 14490.0386472915. The cubic root of 209961220 is about 594.3556048821.

The spelling of 209961220 in words is "two hundred nine million, nine hundred sixty-one thousand, two hundred twenty".