21123253427 has 2 divisors, whose sum is σ = 21123253428. Its totient is φ = 21123253426.

The previous prime is 21123253387. The next prime is 21123253447. The reversal of 21123253427 is 72435232112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21123253427 - 2¹⁴ = 21123237043 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21123253393 and 21123253402.

It is not a weakly prime, because it can be changed into another prime (21123253447) 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 as a sum of consecutive naturals, namely, 10561626713 + 10561626714.

It is an arithmetic number, because the mean of its divisors is an integer number (10561626714).

Almost surely, 2^21123253427 is an apocalyptic number.

21123253427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21123253427 is an equidigital number, since it uses as much as digits as its factorization.

21123253427 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20160, while the sum is 32.

Adding to 21123253427 its reverse (72435232112), we get a palindrome (93558485539).

The spelling of 21123253427 in words is "twenty-one billion, one hundred twenty-three million, two hundred fifty-three thousand, four hundred twenty-seven".