21203121403 has 2 divisors, whose sum is σ = 21203121404. Its totient is φ = 21203121402.

The previous prime is 21203121347. The next prime is 21203121449. The reversal of 21203121403 is 30412130212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21203121403 - 2⁹ = 21203120891 is a prime.

It is not a weakly prime, because it can be changed into another prime (21203121493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601560701 + 10601560702.

It is an arithmetic number, because the mean of its divisors is an integer number (10601560702).

Almost surely, 2^21203121403 is an apocalyptic number.

21203121403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203121403 is an equidigital number, since it uses as much as digits as its factorization.

21203121403 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21203121403 its reverse (30412130212), we get a palindrome (51615251615).

The spelling of 21203121403 in words is "twenty-one billion, two hundred three million, one hundred twenty-one thousand, four hundred three".