21001000012 has 24 divisors (see below), whose sum is σ = 37149184800. Its totient is φ = 10387170816.

The previous prime is 21001000001. The next prime is 21001000019. The reversal of 21001000012 is 21000010012.

It is a junction number, because it is equal to n+sod(n) for n = 21000999959 and 21001000004.

It is not an unprimeable number, because it can be changed into a prime (21001000019) 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, 355314 + ... + 410182.

It is an arithmetic number, because the mean of its divisors is an integer number (1547882700).

Almost surely, 2^21001000012 is an apocalyptic number.

It is an amenable number.

21001000012 is a deficient number, since it is larger than the sum of its proper divisors (16148184788).

21001000012 is a wasteful number, since it uses less digits than its factorization.

21001000012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55905 (or 55903 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 21001000012 its reverse (21000010012), we get a palindrome (42001010024).

It can be divided in two parts, 210010000 and 12, that added together give a palindrome (210010012).

The spelling of 21001000012 in words is "twenty-one billion, one million, twelve", and thus it is an aban number and an uban number.