21123231210 has 48 divisors (see below), whose sum is σ = 54927610920. Its totient is φ = 5632122240.

The previous prime is 21123231193. The next prime is 21123231277. The reversal of 21123231210 is 1213232112.

It can be written as a sum of positive squares in 4 ways, for example, as 20638482921 + 484748289 = 143661^2 + 22017^2 .

It is a super-2 number, since 2×21123231210² (a number of 21 digits) contains 22 as substring.

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

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1232500 + ... + 1249520.

Almost surely, 2^21123231210 is an apocalyptic number.

21123231210 is an abundant number, since it is smaller than the sum of its proper divisors (33804379710).

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

21123231210 is a wasteful number, since it uses less digits than its factorization.

21123231210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30823 (or 30820 counting only the distinct ones).

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

Adding to 21123231210 its reverse (1213232112), we get a palindrome (22336463322).

The spelling of 21123231210 in words is "twenty-one billion, one hundred twenty-three million, two hundred thirty-one thousand, two hundred ten".