21513511221 has 16 divisors (see below), whose sum is σ = 28767851520. Its totient is φ = 14300803440.

The previous prime is 21513511199. The next prime is 21513511231. The reversal of 21513511221 is 12211531512.

It is not a de Polignac number, because 21513511221 - 2⁵ = 21513511189 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21513511191 and 21513511200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513511231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2177190 + ... + 2187048.

It is an arithmetic number, because the mean of its divisors is an integer number (1797990720).

Almost surely, 2^21513511221 is an apocalyptic number.

It is an amenable number.

21513511221 is a deficient number, since it is larger than the sum of its proper divisors (7254340299).

21513511221 is a wasteful number, since it uses less digits than its factorization.

21513511221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11896.

The product of its digits is 600, while the sum is 24.

The spelling of 21513511221 in words is "twenty-one billion, five hundred thirteen million, five hundred eleven thousand, two hundred twenty-one".