21111345521 has 8 divisors (see below), whose sum is σ = 24348603840. Its totient is φ = 17929425168.

The previous prime is 21111345473. The next prime is 21111345529. The reversal of 21111345521 is 12554311112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21111345521 - 2¹⁴ = 21111329137 is a prime.

It is a super-2 number, since 2×21111345521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21111345529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13833671 + ... + 13835196.

It is an arithmetic number, because the mean of its divisors is an integer number (3043575480).

Almost surely, 2^21111345521 is an apocalyptic number.

It is an amenable number.

21111345521 is a deficient number, since it is larger than the sum of its proper divisors (3237258319).

21111345521 is a wasteful number, since it uses less digits than its factorization.

21111345521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27668983.

The product of its digits is 1200, while the sum is 26.

Adding to 21111345521 its reverse (12554311112), we get a palindrome (33665656633).

The spelling of 21111345521 in words is "twenty-one billion, one hundred eleven million, three hundred forty-five thousand, five hundred twenty-one".