20911220 has 36 divisors (see below), whose sum is σ = 48274212. Its totient is φ = 7603200.

The previous prime is 20911213. The next prime is 20911223. The reversal of 20911220 is 2211902.

It can be written as a sum of positive squares in 2 ways, for example, as 3254416 + 17656804 = 1804^2 + 4202^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20911223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1901 + ... + 6740.

Almost surely, 2^20911220 is an apocalyptic number.

20911220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20911220 is an abundant number, since it is smaller than the sum of its proper divisors (27362992).

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

20911220 is a wasteful number, since it uses less digits than its factorization.

20911220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8672 (or 8659 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 20911220 is about 4572.8787431989. The cubic root of 20911220 is about 275.5030791166.

The spelling of 20911220 in words is "twenty million, nine hundred eleven thousand, two hundred twenty".