21402123103447 has 2 divisors, whose sum is σ = 21402123103448. Its totient is φ = 21402123103446.

The previous prime is 21402123103397. The next prime is 21402123103489. The reversal of 21402123103447 is 74430132120412.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21402123103447 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21402123103247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701061551723 + 10701061551724.

It is an arithmetic number, because the mean of its divisors is an integer number (10701061551724).

Almost surely, 2^{21402123103447} is an apocalyptic number.

21402123103447 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402123103447 is an equidigital number, since it uses as much as digits as its factorization.

21402123103447 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32256, while the sum is 34.

Adding to 21402123103447 its reverse (74430132120412), we get a palindrome (95832255223859).

The spelling of 21402123103447 in words is "twenty-one trillion, four hundred two billion, one hundred twenty-three million, one hundred three thousand, four hundred forty-seven".