21107775517 has 4 divisors (see below), whose sum is σ = 21108592800. Its totient is φ = 21106958236.

The previous prime is 21107775511. The next prime is 21107775551. The reversal of 21107775517 is 71557770112.

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 21107775517 - 2¹⁵ = 21107742749 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 (21107775511) 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 3 ways as a sum of consecutive naturals, for example, 368593 + ... + 421990.

It is an arithmetic number, because the mean of its divisors is an integer number (5277148200).

Almost surely, 2^21107775517 is an apocalyptic number.

It is an amenable number.

21107775517 is a deficient number, since it is larger than the sum of its proper divisors (817283).

21107775517 is an equidigital number, since it uses as much as digits as its factorization.

21107775517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 817282.

The product of its (nonzero) digits is 120050, while the sum is 43.

The spelling of 21107775517 in words is "twenty-one billion, one hundred seven million, seven hundred seventy-five thousand, five hundred seventeen".