21443065551 has 16 divisors (see below), whose sum is σ = 32305939200. Its totient is φ = 14053081464.

The previous prime is 21443065541. The next prime is 21443065603. The reversal of 21443065551 is 15556034412.

21443065551 is a `hidden beast` number, since 2 + 1 + 4 + 43 + 0 + 65 + 551 = 666.

It is not a de Polignac number, because 21443065551 - 2¹⁰ = 21443064527 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21443065541) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6728811 + ... + 6731996.

It is an arithmetic number, because the mean of its divisors is an integer number (2019121200).

Almost surely, 2^21443065551 is an apocalyptic number.

21443065551 is a deficient number, since it is larger than the sum of its proper divisors (10862873649).

21443065551 is a wasteful number, since it uses less digits than its factorization.

21443065551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13460875 (or 13460869 counting only the distinct ones).

The product of its (nonzero) digits is 72000, while the sum is 36.

Adding to 21443065551 its reverse (15556034412), we get a palindrome (36999099963).

The spelling of 21443065551 in words is "twenty-one billion, four hundred forty-three million, sixty-five thousand, five hundred fifty-one".