21571497291 has 8 divisors (see below), whose sum is σ = 28868130304. Its totient is φ = 14327931240.

The previous prime is 21571497289. The next prime is 21571497293. The reversal of 21571497291 is 19279417512.

It is an interprime number because it is at equal distance from previous prime (21571497289) and next prime (21571497293).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21571497291 - 2¹ = 21571497289 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21571497291.

It is not an unprimeable number, because it can be changed into a prime (21571497293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13265791 + ... + 13267416.

It is an arithmetic number, because the mean of its divisors is an integer number (3608516288).

Almost surely, 2^21571497291 is an apocalyptic number.

21571497291 is a deficient number, since it is larger than the sum of its proper divisors (7296633013).

21571497291 is a wasteful number, since it uses less digits than its factorization.

21571497291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26533481.

The product of its digits is 317520, while the sum is 48.

The spelling of 21571497291 in words is "twenty-one billion, five hundred seventy-one million, four hundred ninety-seven thousand, two hundred ninety-one".