21201221012 has 12 divisors (see below), whose sum is σ = 37240064820. Its totient is φ = 10561202496.

The previous prime is 21201220981. The next prime is 21201221021. The reversal of 21201221012 is 21012210212.

It can be written as a sum of positive squares in 2 ways, for example, as 6626936836 + 14574284176 = 81406^2 + 120724^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9850793 + ... + 9852944.

It is an arithmetic number, because the mean of its divisors is an integer number (3103338735).

Almost surely, 2^21201221012 is an apocalyptic number.

It is an amenable number.

21201221012 is a deficient number, since it is larger than the sum of its proper divisors (16038843808).

21201221012 is a wasteful number, since it uses less digits than its factorization.

21201221012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19704010 (or 19704008 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21201221012 its reverse (21012210212), we get a palindrome (42213431224).

The spelling of 21201221012 in words is "twenty-one billion, two hundred one million, two hundred twenty-one thousand, twelve".