21811658447 has 16 divisors (see below), whose sum is σ = 22474755072. Its totient is φ = 21159193440.

The previous prime is 21811658443. The next prime is 21811658459. The reversal of 21811658447 is 74485611812.

It is a cyclic number.

It is not a de Polignac number, because 21811658447 - 2² = 21811658443 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 (21811658443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5244893 + ... + 5249049.

It is an arithmetic number, because the mean of its divisors is an integer number (1404672192).

Almost surely, 2^21811658447 is an apocalyptic number.

21811658447 is a deficient number, since it is larger than the sum of its proper divisors (663096625).

21811658447 is a wasteful number, since it uses less digits than its factorization.

21811658447 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5398.

The product of its digits is 430080, while the sum is 47.

The spelling of 21811658447 in words is "twenty-one billion, eight hundred eleven million, six hundred fifty-eight thousand, four hundred forty-seven".