21221010012 has 12 divisors (see below), whose sum is σ = 49515690056. Its totient is φ = 7073670000.

The previous prime is 21221010001. The next prime is 21221010017. The reversal of 21221010012 is 21001012212.

It is a tau number, because it is divible by the number of its divisors (12).

It is a Harshad number since it is a multiple of its sum of digits (12), and also a Moran number because the ratio is a prime number: 1768417501 = 21221010012 / (2 + 1 + 2 + 2 + 1 + 0 + 1 + 0 + 0 + 1 + 2).

It is a self number, because there is not a number n which added to its sum of digits gives 21221010012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221010017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 884208739 + ... + 884208762.

Almost surely, 2^21221010012 is an apocalyptic number.

It is an amenable number.

21221010012 is an abundant number, since it is smaller than the sum of its proper divisors (28294680044).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221010012 is a wasteful number, since it uses less digits than its factorization.

21221010012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1768417508 (or 1768417506 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

Adding to 21221010012 its reverse (21001012212), we get a palindrome (42222022224).

It can be divided in two parts, 212210 and 10012, that added together give a palindrome (222222).

The spelling of 21221010012 in words is "twenty-one billion, two hundred twenty-one million, ten thousand, twelve".