21100071 has 4 divisors (see below), whose sum is σ = 28133432. Its totient is φ = 14066712.

The previous prime is 21100069. The next prime is 21100087. The reversal of 21100071 is 17000112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21100071 - 2¹ = 21100069 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 (21100021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3516676 + ... + 3516681.

It is an arithmetic number, because the mean of its divisors is an integer number (7033358).

Almost surely, 2^21100071 is an apocalyptic number.

21100071 is a deficient number, since it is larger than the sum of its proper divisors (7033361).

21100071 is an equidigital number, since it uses as much as digits as its factorization.

21100071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033360.

The product of its (nonzero) digits is 14, while the sum is 12.

The square root of 21100071 is about 4593.4813594919. The cubic root of 21100071 is about 276.3299587683.

Adding to 21100071 its reverse (17000112), we get a palindrome (38100183).

The spelling of 21100071 in words is "twenty-one million, one hundred thousand, seventy-one".