21120031221 has 16 divisors (see below), whose sum is σ = 29387750784. Its totient is φ = 13466306304.

The previous prime is 21120031217. The next prime is 21120031333. The reversal of 21120031221 is 12213002112.

It is not a de Polignac number, because 21120031221 - 2² = 21120031217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21120031221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120031201) 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, 1181865 + ... + 1199601.

It is an arithmetic number, because the mean of its divisors is an integer number (1836734424).

Almost surely, 2^21120031221 is an apocalyptic number.

It is an amenable number.

21120031221 is a deficient number, since it is larger than the sum of its proper divisors (8267719563).

21120031221 is a wasteful number, since it uses less digits than its factorization.

21120031221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35020.

The product of its (nonzero) digits is 48, while the sum is 15.

Adding to 21120031221 its reverse (12213002112), we get a palindrome (33333033333).

The spelling of 21120031221 in words is "twenty-one billion, one hundred twenty million, thirty-one thousand, two hundred twenty-one".