21101210001 has 12 divisors (see below), whose sum is σ = 31303297012. Its totient is φ = 13687271136.

The previous prime is 21101209979. The next prime is 21101210003. The reversal of 21101210001 is 10001210112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20398694976 + 702515025 = 142824^2 + 26505^2 .

It is not a de Polignac number, because 21101210001 - 2¹³ = 21101201809 is a prime.

It is a super-2 number, since 2×21101210001² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21101210003) 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 in 11 ways as a sum of consecutive naturals, for example, 31683166 + ... + 31683831.

Almost surely, 2^21101210001 is an apocalyptic number.

It is an amenable number.

21101210001 is a deficient number, since it is larger than the sum of its proper divisors (10202087011).

21101210001 is a wasteful number, since it uses less digits than its factorization.

21101210001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63367040 (or 63367037 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21101210001 its reverse (10001210112), we get a palindrome (31102420113).

The spelling of 21101210001 in words is "twenty-one billion, one hundred one million, two hundred ten thousand, one".