21110623717 has 4 divisors (see below), whose sum is σ = 21110920300. Its totient is φ = 21110327136.

The previous prime is 21110623693. The next prime is 21110623733. The reversal of 21110623717 is 71732601112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15495519361 + 5615104356 = 124481^2 + 74934^2 .

It is a 3-Lehmer number, since φ(21110623717) divides (21110623717-1)³.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21110623717 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 (21110623757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29659 + ... + 207607.

It is an arithmetic number, because the mean of its divisors is an integer number (5277730075).

It is a Poulet number, since it divides 2^21110623716-1.

Almost surely, 2^21110623717 is an apocalyptic number.

21110623717 is the 118633-rd pentagonal number.

It is an amenable number.

21110623717 is a deficient number, since it is larger than the sum of its proper divisors (296583).

21110623717 is a wasteful number, since it uses less digits than its factorization.

21110623717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296582.

The product of its (nonzero) digits is 3528, while the sum is 31.

The spelling of 21110623717 in words is "twenty-one billion, one hundred ten million, six hundred twenty-three thousand, seven hundred seventeen".