21020121012 has 24 divisors (see below), whose sum is σ = 53505762912. Its totient is φ = 6369733600.

The previous prime is 21020121007. The next prime is 21020121029. The reversal of 21020121012 is 21012102012.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 79621539 + ... + 79621802.

It is an arithmetic number, because the mean of its divisors is an integer number (2229406788).

Almost surely, 2^21020121012 is an apocalyptic number.

21020121012 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21020121012 is an abundant number, since it is smaller than the sum of its proper divisors (32485641900).

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

21020121012 is a wasteful number, since it uses less digits than its factorization.

21020121012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159243359 (or 159243357 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21020121012 its reverse (21012102012), we get a palindrome (42032223024).

The spelling of 21020121012 in words is "twenty-one billion, twenty million, one hundred twenty-one thousand, twelve".