21306237451 has 2 divisors, whose sum is σ = 21306237452. Its totient is φ = 21306237450.

The previous prime is 21306237431. The next prime is 21306237487. The reversal of 21306237451 is 15473260312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21306237451 - 2¹⁵ = 21306204683 is a prime.

It is not a weakly prime, because it can be changed into another prime (21306237431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10653118725 + 10653118726.

It is an arithmetic number, because the mean of its divisors is an integer number (10653118726).

Almost surely, 2^21306237451 is an apocalyptic number.

21306237451 is a deficient number, since it is larger than the sum of its proper divisors (1).

21306237451 is an equidigital number, since it uses as much as digits as its factorization.

21306237451 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 30240, while the sum is 34.

Adding to 21306237451 its reverse (15473260312), we get a palindrome (36779497763).

The spelling of 21306237451 in words is "twenty-one billion, three hundred six million, two hundred thirty-seven thousand, four hundred fifty-one".