21000020012 has 6 divisors (see below), whose sum is σ = 36750035028. Its totient is φ = 10500010004.

The previous prime is 21000019991. The next prime is 21000020053. The reversal of 21000020012 is 21002000012.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2625002498 + ... + 2625002505.

It is an arithmetic number, because the mean of its divisors is an integer number (6125005838).

Almost surely, 2^21000020012 is an apocalyptic number.

It is an amenable number.

21000020012 is a deficient number, since it is larger than the sum of its proper divisors (15750015016).

21000020012 is a wasteful number, since it uses less digits than its factorization.

21000020012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5250005007 (or 5250005005 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 8.

Adding to 21000020012 its reverse (21002000012), we get a palindrome (42002020024).

The spelling of 21000020012 in words is "twenty-one billion, twenty thousand, twelve".