21221312021 has 32 divisors (see below), whose sum is σ = 27944044800. Its totient is φ = 15645934080.

The previous prime is 21221312009. The next prime is 21221312023. The reversal of 21221312021 is 12021312212.

It is not a de Polignac number, because 21221312021 - 2¹⁰ = 21221310997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221312023) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4865 + ... + 206073.

It is an arithmetic number, because the mean of its divisors is an integer number (873251400).

Almost surely, 2^21221312021 is an apocalyptic number.

It is an amenable number.

21221312021 is a deficient number, since it is larger than the sum of its proper divisors (6722732779).

21221312021 is a wasteful number, since it uses less digits than its factorization.

21221312021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 201309.

The product of its (nonzero) digits is 96, while the sum is 17.

Adding to 21221312021 its reverse (12021312212), we get a palindrome (33242624233).

The spelling of 21221312021 in words is "twenty-one billion, two hundred twenty-one million, three hundred twelve thousand, twenty-one".