21243123412451 has 2 divisors, whose sum is σ = 21243123412452. Its totient is φ = 21243123412450.

The previous prime is 21243123412409. The next prime is 21243123412481. The reversal of 21243123412451 is 15421432134212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21243123412451 - 2³⁰ = 21242049670627 is a prime.

It is not a weakly prime, because it can be changed into another prime (21243123412481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621561706225 + 10621561706226.

It is an arithmetic number, because the mean of its divisors is an integer number (10621561706226).

Almost surely, 2^{21243123412451} is an apocalyptic number.

21243123412451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243123412451 is an equidigital number, since it uses as much as digits as its factorization.

21243123412451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 46080, while the sum is 35.

Adding to 21243123412451 its reverse (15421432134212), we get a palindrome (36664555546663).

The spelling of 21243123412451 in words is "twenty-one trillion, two hundred forty-three billion, one hundred twenty-three million, four hundred twelve thousand, four hundred fifty-one".