21000001012 has 6 divisors (see below), whose sum is σ = 36750001778. Its totient is φ = 10500000504.

The previous prime is 21000000979. The next prime is 21000001013. The reversal of 21000001012 is 21010000012.

It can be written as a sum of positive squares in only one way, i.e., 14095388176 + 6904612836 = 118724^2 + 83094^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21000000986 and 21000001004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000001013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2625000123 + ... + 2625000130.

Almost surely, 2^21000001012 is an apocalyptic number.

It is an amenable number.

21000001012 is a deficient number, since it is larger than the sum of its proper divisors (15750000766).

21000001012 is a wasteful number, since it uses less digits than its factorization.

21000001012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5250000257 (or 5250000255 counting only the distinct ones).

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

Adding to 21000001012 its reverse (21010000012), we get a palindrome (42010001024).

It can be divided in two parts, 2100000 and 1012, that added together give a palindrome (2101012).

The spelling of 21000001012 in words is "twenty-one billion, one thousand, twelve".