21012212122123 has 4 divisors (see below), whose sum is σ = 21012292746360. Its totient is φ = 21012131497888.

The previous prime is 21012212122117. The next prime is 21012212122127. The reversal of 21012212122123 is 32122121221012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012212122123 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21012212122094 and 21012212122103.

It is not an unprimeable number, because it can be changed into a prime (21012212122127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39919918 + ... + 40442851.

It is an arithmetic number, because the mean of its divisors is an integer number (5253073186590).

Almost surely, 2^{21012212122123} is an apocalyptic number.

21012212122123 is a deficient number, since it is larger than the sum of its proper divisors (80624237).

21012212122123 is an equidigital number, since it uses as much as digits as its factorization.

21012212122123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80624236.

The product of its (nonzero) digits is 384, while the sum is 22.

Adding to 21012212122123 its reverse (32122121221012), we get a palindrome (53134333343135).

The spelling of 21012212122123 in words is "twenty-one trillion, twelve billion, two hundred twelve million, one hundred twenty-two thousand, one hundred twenty-three".