21122311521 has 16 divisors (see below), whose sum is σ = 30513219264. Its totient is φ = 12944999424.

The previous prime is 21122311459. The next prime is 21122311537. The reversal of 21122311521 is 12511322112.

It is not a de Polignac number, because 21122311521 - 2⁹ = 21122311009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21122311541) 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, 4813656 + ... + 4818041.

It is an arithmetic number, because the mean of its divisors is an integer number (1907076204).

Almost surely, 2^21122311521 is an apocalyptic number.

It is an amenable number.

21122311521 is a deficient number, since it is larger than the sum of its proper divisors (9390907743).

21122311521 is a wasteful number, since it uses less digits than its factorization.

21122311521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9631760.

The product of its digits is 240, while the sum is 21.

Adding to 21122311521 its reverse (12511322112), we get a palindrome (33633633633).

The spelling of 21122311521 in words is "twenty-one billion, one hundred twenty-two million, three hundred eleven thousand, five hundred twenty-one".