21211121020 has 12 divisors (see below), whose sum is σ = 44543354184. Its totient is φ = 8484448400.

The previous prime is 21211121003. The next prime is 21211121021. The reversal of 21211121020 is 2012111212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211121021) 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, 530278006 + ... + 530278045.

It is an arithmetic number, because the mean of its divisors is an integer number (3711946182).

Almost surely, 2^21211121020 is an apocalyptic number.

21211121020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21211121020 is an abundant number, since it is smaller than the sum of its proper divisors (23332233164).

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

21211121020 is a wasteful number, since it uses less digits than its factorization.

21211121020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1060556060 (or 1060556058 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21211121020 its reverse (2012111212), we get a palindrome (23223232232).

The spelling of 21211121020 in words is "twenty-one billion, two hundred eleven million, one hundred twenty-one thousand, twenty".