21001320012 has 24 divisors (see below), whose sum is σ = 50045700096. Its totient is φ = 6851494288.

The previous prime is 21001320007. The next prime is 21001320017. The reversal of 21001320012 is 21002310012.

It is an interprime number because it is at equal distance from previous prime (21001320007) and next prime (21001320017).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a self number, because there is not a number n which added to its sum of digits gives 21001320012.

It is not an unprimeable number, because it can be changed into a prime (21001320017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18617628 + ... + 18618755.

It is an arithmetic number, because the mean of its divisors is an integer number (2085237504).

Almost surely, 2^21001320012 is an apocalyptic number.

It is an amenable number.

21001320012 is an abundant number, since it is smaller than the sum of its proper divisors (29044380084).

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

21001320012 is a wasteful number, since it uses less digits than its factorization.

21001320012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37236437 (or 37236435 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21001320012 its reverse (21002310012), we get a palindrome (42003630024).

The spelling of 21001320012 in words is "twenty-one billion, one million, three hundred twenty thousand, twelve".