21102028117 has 4 divisors (see below), whose sum is σ = 21102319296. Its totient is φ = 21101736940.

The previous prime is 21102028111. The next prime is 21102028127. The reversal of 21102028117 is 71182020112.

It is a happy number.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21102028117 - 2¹⁵ = 21101995349 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21102028091 and 21102028100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102028111) 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 3 ways as a sum of consecutive naturals, for example, 58242 + ... + 213532.

It is an arithmetic number, because the mean of its divisors is an integer number (5275579824).

Almost surely, 2^21102028117 is an apocalyptic number.

It is an amenable number.

21102028117 is a deficient number, since it is larger than the sum of its proper divisors (291179).

21102028117 is a wasteful number, since it uses less digits than its factorization.

21102028117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 291178.

The product of its (nonzero) digits is 448, while the sum is 25.

Adding to 21102028117 its reverse (71182020112), we get a palindrome (92284048229).

The spelling of 21102028117 in words is "twenty-one billion, one hundred two million, twenty-eight thousand, one hundred seventeen".