21020320120123 has 4 divisors (see below), whose sum is σ = 21072739871448. Its totient is φ = 20967900368800.

The previous prime is 21020320120097. The next prime is 21020320120169. The reversal of 21020320120123 is 32102102302012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21020320120123 - 2⁵ = 21020320120091 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21020320120123.

It is not an unprimeable number, because it can be changed into a prime (21020320120183) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26209875061 + ... + 26209875862.

It is an arithmetic number, because the mean of its divisors is an integer number (5268184967862).

Almost surely, 2^{21020320120123} is an apocalyptic number.

21020320120123 is a deficient number, since it is larger than the sum of its proper divisors (52419751325).

21020320120123 is an equidigital number, since it uses as much as digits as its factorization.

21020320120123 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52419751324.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21020320120123 its reverse (32102102302012), we get a palindrome (53122422422135).

The spelling of 21020320120123 in words is "twenty-one trillion, twenty billion, three hundred twenty million, one hundred twenty thousand, one hundred twenty-three".