21020121123123 has 64 divisors (see below), whose sum is σ = 29563630387200. Its totient is φ = 13258958106240.

The previous prime is 21020121123121. The next prime is 21020121123139. The reversal of 21020121123123 is 32132112102012.

It is not a de Polignac number, because 21020121123123 - 2¹ = 21020121123121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21020121123123.

It is not an unprimeable number, because it can be changed into a prime (21020121123121) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 8986797088 + ... + 8986799426.

It is an arithmetic number, because the mean of its divisors is an integer number (461931724800).

Almost surely, 2^{21020121123123} is an apocalyptic number.

21020121123123 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21020121123123 is a deficient number, since it is larger than the sum of its proper divisors (8543509264077).

21020121123123 is a wasteful number, since it uses less digits than its factorization.

21020121123123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5112.

The product of its (nonzero) digits is 288, while the sum is 21.

Adding to 21020121123123 its reverse (32132112102012), we get a palindrome (53152233225135).

The spelling of 21020121123123 in words is "twenty-one trillion, twenty billion, one hundred twenty-one million, one hundred twenty-three thousand, one hundred twenty-three".