21231213120 has 504 divisors, whose sum is σ = 79842875112. Its totient is φ = 5175705600.

The previous prime is 21231213103. The next prime is 21231213137. The reversal of 21231213120 is 2131213212.

It is an interprime number because it is at equal distance from previous prime (21231213103) and next prime (21231213137).

It can be written as a sum of positive squares in 12 ways, for example, as 16198161984 + 5033051136 = 127272^2 + 70944^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21231213093 and 21231213102.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 88096200 + ... + 88096440.

It is an arithmetic number, because the mean of its divisors is an integer number (158418403).

Almost surely, 2^21231213120 is an apocalyptic number.

21231213120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21231213120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39921437556).

21231213120 is an abundant number, since it is smaller than the sum of its proper divisors (58611661992).

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

21231213120 is a wasteful number, since it uses less digits than its factorization.

21231213120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 471 (or 445 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21231213120 its reverse (2131213212), we get a palindrome (23362426332).

The spelling of 21231213120 in words is "twenty-one billion, two hundred thirty-one million, two hundred thirteen thousand, one hundred twenty".