21121213020 has 24 divisors (see below), whose sum is σ = 59139396624. Its totient is φ = 5632323456.

The previous prime is 21121213019. The next prime is 21121213027. The reversal of 21121213020 is 2031212112.

It is a super-2 number, since 2×21121213020² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121213027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 176010049 + ... + 176010168.

It is an arithmetic number, because the mean of its divisors is an integer number (2464141526).

Almost surely, 2^21121213020 is an apocalyptic number.

21121213020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121213020 is an abundant number, since it is smaller than the sum of its proper divisors (38018183604).

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

21121213020 is a wasteful number, since it uses less digits than its factorization.

21121213020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352020229 (or 352020227 counting only the distinct ones).

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

Adding to 21121213020 its reverse (2031212112), we get a palindrome (23152425132).

The spelling of 21121213020 in words is "twenty-one billion, one hundred twenty-one million, two hundred thirteen thousand, twenty".