21306237461 has 4 divisors (see below), whose sum is σ = 22427618400. Its totient is φ = 20184856524.

The previous prime is 21306237451. The next prime is 21306237487. The reversal of 21306237461 is 16473260312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21306237461 - 2¹⁰ = 21306236437 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a 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 in 3 ways as a sum of consecutive naturals, for example, 560690441 + ... + 560690478.

It is an arithmetic number, because the mean of its divisors is an integer number (5606904600).

Almost surely, 2^21306237461 is an apocalyptic number.

It is an amenable number.

21306237461 is a deficient number, since it is larger than the sum of its proper divisors (1121380939).

21306237461 is a wasteful number, since it uses less digits than its factorization.

21306237461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1121380938.

The product of its (nonzero) digits is 36288, while the sum is 35.

Adding to 21306237461 its reverse (16473260312), we get a palindrome (37779497773).

The spelling of 21306237461 in words is "twenty-one billion, three hundred six million, two hundred thirty-seven thousand, four hundred sixty-one".