21364240261 has 16 divisors (see below), whose sum is σ = 26298243328. Its totient is φ = 16901136000.

The previous prime is 21364240223. The next prime is 21364240273. The reversal of 21364240261 is 16204246312.

It is not a de Polignac number, because 21364240261 - 2⁷ = 21364240133 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364240201) 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 15 ways as a sum of consecutive naturals, for example, 872536 + ... + 896686.

It is an arithmetic number, because the mean of its divisors is an integer number (1643640208).

Almost surely, 2^21364240261 is an apocalyptic number.

It is an amenable number.

21364240261 is a deficient number, since it is larger than the sum of its proper divisors (4934003067).

21364240261 is a wasteful number, since it uses less digits than its factorization.

21364240261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33892.

The product of its (nonzero) digits is 13824, while the sum is 31.

Adding to 21364240261 its reverse (16204246312), we get a palindrome (37568486573).

The spelling of 21364240261 in words is "twenty-one billion, three hundred sixty-four million, two hundred forty thousand, two hundred sixty-one".