21871270549 has 4 divisors (see below), whose sum is σ = 21871964736. Its totient is φ = 21870576364.

The previous prime is 21871270529. The next prime is 21871270573. The reversal of 21871270549 is 94507217812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21871270549 is a prime.

It is a super-2 number, since 2×21871270549² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21871270499 and 21871270508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871270529) 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, 297469 + ... + 363634.

It is an arithmetic number, because the mean of its divisors is an integer number (5467991184).

Almost surely, 2^21871270549 is an apocalyptic number.

It is an amenable number.

21871270549 is a deficient number, since it is larger than the sum of its proper divisors (694187).

21871270549 is an equidigital number, since it uses as much as digits as its factorization.

21871270549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694186.

The product of its (nonzero) digits is 282240, while the sum is 46.

The spelling of 21871270549 in words is "twenty-one billion, eight hundred seventy-one million, two hundred seventy thousand, five hundred forty-nine".