21115500671 has 4 divisors (see below), whose sum is σ = 21118251000. Its totient is φ = 21112750344.

The previous prime is 21115500649. The next prime is 21115500691. The reversal of 21115500671 is 17600551112.

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 21115500671 - 2³⁴ = 3935631487 is a prime.

It is a super-3 number, since 3×21115500671³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115500691) 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, 1363616 + ... + 1379013.

It is an arithmetic number, because the mean of its divisors is an integer number (5279562750).

Almost surely, 2^21115500671 is an apocalyptic number.

21115500671 is a deficient number, since it is larger than the sum of its proper divisors (2750329).

21115500671 is an equidigital number, since it uses as much as digits as its factorization.

21115500671 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2750328.

The product of its (nonzero) digits is 2100, while the sum is 29.

The spelling of 21115500671 in words is "twenty-one billion, one hundred fifteen million, five hundred thousand, six hundred seventy-one".