21345130681 has 16 divisors (see below), whose sum is σ = 25519190400. Its totient is φ = 17466438528.

The previous prime is 21345130679. The next prime is 21345130711. The reversal of 21345130681 is 18603154312.

It is not a de Polignac number, because 21345130681 - 2¹ = 21345130679 is a prime.

It is a super-2 number, since 2×21345130681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21345130661) 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 in 15 ways as a sum of consecutive naturals, for example, 572655 + ... + 608788.

It is an arithmetic number, because the mean of its divisors is an integer number (1594949400).

Almost surely, 2^21345130681 is an apocalyptic number.

It is an amenable number.

21345130681 is a deficient number, since it is larger than the sum of its proper divisors (4174059719).

21345130681 is a wasteful number, since it uses less digits than its factorization.

21345130681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1181568.

The product of its (nonzero) digits is 17280, while the sum is 34.

Adding to 21345130681 its reverse (18603154312), we get a palindrome (39948284993).

The spelling of 21345130681 in words is "twenty-one billion, three hundred forty-five million, one hundred thirty thousand, six hundred eighty-one".