20021221131 has 4 divisors (see below), whose sum is σ = 26694961512. Its totient is φ = 13347480752.

The previous prime is 20021221127. The next prime is 20021221159. The reversal of 20021221131 is 13112212002.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20021221131 - 2² = 20021221127 is a prime.

It is a super-2 number, since 2×20021221131² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20021221131.

It is not an unprimeable number, because it can be changed into a prime (20021225131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3336870186 + ... + 3336870191.

It is an arithmetic number, because the mean of its divisors is an integer number (6673740378).

Almost surely, 2^20021221131 is an apocalyptic number.

20021221131 is a deficient number, since it is larger than the sum of its proper divisors (6673740381).

20021221131 is an equidigital number, since it uses as much as digits as its factorization.

20021221131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6673740380.

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

Adding to 20021221131 its reverse (13112212002), we get a palindrome (33133433133).

The spelling of 20021221131 in words is "twenty billion, twenty-one million, two hundred twenty-one thousand, one hundred thirty-one".