21521135311 has 4 divisors (see below), whose sum is σ = 23176607272. Its totient is φ = 19865663352.

The previous prime is 21521135309. The next prime is 21521135333. The reversal of 21521135311 is 11353112512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21521135311 - 2¹ = 21521135309 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521135411) 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 3 ways as a sum of consecutive naturals, for example, 827735961 + ... + 827735986.

It is an arithmetic number, because the mean of its divisors is an integer number (5794151818).

Almost surely, 2^21521135311 is an apocalyptic number.

21521135311 is a deficient number, since it is larger than the sum of its proper divisors (1655471961).

21521135311 is a wasteful number, since it uses less digits than its factorization.

21521135311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1655471960.

The product of its digits is 900, while the sum is 25.

Adding to 21521135311 its reverse (11353112512), we get a palindrome (32874247823).

The spelling of 21521135311 in words is "twenty-one billion, five hundred twenty-one million, one hundred thirty-five thousand, three hundred eleven".