21305431511 has 32 divisors (see below), whose sum is σ = 26886238848. Its totient is φ = 16430837760.

The previous prime is 21305431489. The next prime is 21305431513. The reversal of 21305431511 is 11513450312.

It is a cyclic number.

It is not a de Polignac number, because 21305431511 - 2¹⁸ = 21305169367 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305431513) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5792405 + ... + 5796081.

It is an arithmetic number, because the mean of its divisors is an integer number (840194964).

Almost surely, 2^21305431511 is an apocalyptic number.

21305431511 is a deficient number, since it is larger than the sum of its proper divisors (5580807337).

21305431511 is a wasteful number, since it uses less digits than its factorization.

21305431511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5291.

The product of its (nonzero) digits is 1800, while the sum is 26.

Adding to 21305431511 its reverse (11513450312), we get a palindrome (32818881823).

The spelling of 21305431511 in words is "twenty-one billion, three hundred five million, four hundred thirty-one thousand, five hundred eleven".