21361579551 has 96 divisors (see below), whose sum is σ = 36620320320. Its totient is φ = 12257796096.

The previous prime is 21361579543. The next prime is 21361579553. The reversal of 21361579551 is 15597516312.

21361579551 is a `hidden beast` number, since 2 + 13 + 6 + 15 + 79 + 551 = 666.

It is not a de Polignac number, because 21361579551 - 2³ = 21361579543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21361579497 and 21361579506.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361579553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 8764305 + ... + 8766741.

It is an arithmetic number, because the mean of its divisors is an integer number (381461670).

Almost surely, 2^21361579551 is an apocalyptic number.

21361579551 is a deficient number, since it is larger than the sum of its proper divisors (15258740769).

21361579551 is a wasteful number, since it uses less digits than its factorization.

21361579551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2602 (or 2583 counting only the distinct ones).

The product of its digits is 283500, while the sum is 45.

The spelling of 21361579551 in words is "twenty-one billion, three hundred sixty-one million, five hundred seventy-nine thousand, five hundred fifty-one".