20021220 has 36 divisors (see below), whose sum is σ = 60731580. Its totient is φ = 5338944.

The previous prime is 20021213. The next prime is 20021233. The reversal of 20021220 is 2212002.

It can be written as a sum of positive squares in 2 ways, for example, as 8892324 + 11128896 = 2982^2 + 3336^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55435 + ... + 55794.

Almost surely, 2^20021220 is an apocalyptic number.

20021220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20021220 is an abundant number, since it is smaller than the sum of its proper divisors (40710360).

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

20021220 is a wasteful number, since it uses less digits than its factorization.

20021220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111244 (or 111239 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 20021220 is about 4474.5077941602. The cubic root of 20021220 is about 271.5377276306.

Adding to 20021220 its reverse (2212002), we get a palindrome (22233222).

The spelling of 20021220 in words is "twenty million, twenty-one thousand, two hundred twenty".