123012205105421 has 4 divisors (see below), whose sum is σ = 127254005281500. Its totient is φ = 118770404929344.

The previous prime is 123012205105381. The next prime is 123012205105441. The reversal of 123012205105421 is 124501502210321.

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

It can be written as a sum of positive squares in 2 ways, for example, as 77732629525321 + 45279575580100 = 8816611^2 + 6729010^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-123012205105421 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 4241800176049 = 123012205105421 / (1 + 2 + 3 + 0 + 1 + 2 + 2 + 0 + 5 + 1 + 0 + 5 + 4 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123012205105441) 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, 2120900087996 + ... + 2120900088053.

It is an arithmetic number, because the mean of its divisors is an integer number (31813501320375).

Almost surely, 2^{123012205105421} is an apocalyptic number.

It is an amenable number.

123012205105421 is a deficient number, since it is larger than the sum of its proper divisors (4241800176079).

123012205105421 is an equidigital number, since it uses as much as digits as its factorization.

123012205105421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4241800176078.

The product of its (nonzero) digits is 4800, while the sum is 29.

Adding to 123012205105421 its reverse (124501502210321), we get a palindrome (247513707315742).

The spelling of 123012205105421 in words is "one hundred twenty-three trillion, twelve billion, two hundred five million, one hundred five thousand, four hundred twenty-one".