21101210205 has 8 divisors (see below), whose sum is σ = 33761936352. Its totient is φ = 11253978768.

The previous prime is 21101210201. The next prime is 21101210213. The reversal of 21101210205 is 50201210112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21101210205 - 2² = 21101210201 is a prime.

It is a super-2 number, since 2×21101210205² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15), and also a Moran number because the ratio is a prime number: 1406747347 = 21101210205 / (2 + 1 + 1 + 0 + 1 + 2 + 1 + 0 + 2 + 0 + 5).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101210201) 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, 703373659 + ... + 703373688.

It is an arithmetic number, because the mean of its divisors is an integer number (4220242044).

Almost surely, 2^21101210205 is an apocalyptic number.

It is an amenable number.

21101210205 is a deficient number, since it is larger than the sum of its proper divisors (12660726147).

21101210205 is a wasteful number, since it uses less digits than its factorization.

21101210205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1406747355.

The product of its (nonzero) digits is 40, while the sum is 15.

Adding to 21101210205 its reverse (50201210112), we get a palindrome (71302420317).

The spelling of 21101210205 in words is "twenty-one billion, one hundred one million, two hundred ten thousand, two hundred five".