21123121403 has 8 divisors (see below), whose sum is σ = 22336331136. Its totient is φ = 19943150400.

The previous prime is 21123121391. The next prime is 21123121421. The reversal of 21123121403 is 30412132112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21123121403 - 2⁸ = 21123121147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21123121493) 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 7 ways as a sum of consecutive naturals, for example, 8308376 + ... + 8310917.

It is an arithmetic number, because the mean of its divisors is an integer number (2792041392).

Almost surely, 2^21123121403 is an apocalyptic number.

21123121403 is a deficient number, since it is larger than the sum of its proper divisors (1213209733).

21123121403 is a wasteful number, since it uses less digits than its factorization.

21123121403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16619365.

The product of its (nonzero) digits is 288, while the sum is 20.

Adding to 21123121403 its reverse (30412132112), we get a palindrome (51535253515).

The spelling of 21123121403 in words is "twenty-one billion, one hundred twenty-three million, one hundred twenty-one thousand, four hundred three".