21123131221424 has 80 divisors (see below), whose sum is σ = 45942353251200. Its totient is φ = 9349374108672.

The previous prime is 21123131221343. The next prime is 21123131221427. The reversal of 21123131221424 is 42412213132112.

It is a super-2 number, since 2×21123131221424² (a number of 27 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21123131221427) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13984142 + ... + 15420845.

It is an arithmetic number, because the mean of its divisors is an integer number (574279415640).

Almost surely, 2^{21123131221424} is an apocalyptic number.

It is an amenable number.

21123131221424 is an abundant number, since it is smaller than the sum of its proper divisors (24819222029776).

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

21123131221424 is a wasteful number, since it uses less digits than its factorization.

21123131221424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29405170 (or 29405164 counting only the distinct ones).

The product of its digits is 4608, while the sum is 29.

Adding to 21123131221424 its reverse (42412213132112), we get a palindrome (63535344353536).

The spelling of 21123131221424 in words is "twenty-one trillion, one hundred twenty-three billion, one hundred thirty-one million, two hundred twenty-one thousand, four hundred twenty-four".