21015710671 has 4 divisors (see below), whose sum is σ = 21051150912. Its totient is φ = 20980270432.

The previous prime is 21015710659. The next prime is 21015710689. The reversal of 21015710671 is 17601751012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21015710671 - 2⁷ = 21015710543 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 (21015711671) 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, 17719231 + ... + 17720416.

It is an arithmetic number, because the mean of its divisors is an integer number (5262787728).

Almost surely, 2^21015710671 is an apocalyptic number.

21015710671 is a deficient number, since it is larger than the sum of its proper divisors (35440241).

21015710671 is an equidigital number, since it uses as much as digits as its factorization.

21015710671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35440240.

The product of its (nonzero) digits is 2940, while the sum is 31.

The spelling of 21015710671 in words is "twenty-one billion, fifteen million, seven hundred ten thousand, six hundred seventy-one".