21548511847 has 4 divisors (see below), whose sum is σ = 21548805520. Its totient is φ = 21548218176.

The previous prime is 21548511841. The next prime is 21548511851. The reversal of 21548511847 is 74811584512.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21548511847 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21548511797 and 21548511806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21548511841) 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, 68158 + ... + 218500.

It is an arithmetic number, because the mean of its divisors is an integer number (5387201380).

Almost surely, 2^21548511847 is an apocalyptic number.

21548511847 is a deficient number, since it is larger than the sum of its proper divisors (293673).

21548511847 is a wasteful number, since it uses less digits than its factorization.

21548511847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 293672.

The product of its digits is 358400, while the sum is 46.

It can be divided in two parts, 2154 and 8511847, that added together give a triangular number (8514001 = T₄₁₂₆).

The spelling of 21548511847 in words is "twenty-one billion, five hundred forty-eight million, five hundred eleven thousand, eight hundred forty-seven".