20021213121 has 128 divisors (see below), whose sum is σ = 36284129280. Its totient is φ = 9517989888.

The previous prime is 20021213077. The next prime is 20021213129. The reversal of 20021213121 is 12131212002.

It is not a de Polignac number, because 20021213121 - 2⁶ = 20021213057 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20021213121.

It is not an unprimeable number, because it can be changed into a prime (20021213129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 30660031 + ... + 30660683.

It is an arithmetic number, because the mean of its divisors is an integer number (283469760).

Almost surely, 2^20021213121 is an apocalyptic number.

20021213121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20021213121 is a deficient number, since it is larger than the sum of its proper divisors (16262916159).

20021213121 is a wasteful number, since it uses less digits than its factorization.

20021213121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 975.

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 20021213121 its reverse (12131212002), we get a palindrome (32152425123).

It can be divided in two parts, 2002 and 1213121, that multiplied together give a palindrome (2428668242).

The spelling of 20021213121 in words is "twenty billion, twenty-one million, two hundred thirteen thousand, one hundred twenty-one".