21275871391 has 4 divisors (see below), whose sum is σ = 21276299632. Its totient is φ = 21275443152.

The previous prime is 21275871371. The next prime is 21275871437. The reversal of 21275871391 is 19317857212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21275871391 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 (21275871301) 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, 128070 + ... + 242803.

It is an arithmetic number, because the mean of its divisors is an integer number (5319074908).

Almost surely, 2^21275871391 is an apocalyptic number.

21275871391 is a deficient number, since it is larger than the sum of its proper divisors (428241).

21275871391 is an equidigital number, since it uses as much as digits as its factorization.

21275871391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 428240.

The product of its digits is 211680, while the sum is 46.

The spelling of 21275871391 in words is "twenty-one billion, two hundred seventy-five million, eight hundred seventy-one thousand, three hundred ninety-one".