21211101 has 12 divisors (see below), whose sum is σ = 31466812. Its totient is φ = 13758336.

The previous prime is 21211079. The next prime is 21211109. The reversal of 21211101 is 10111212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9308601 + 11902500 = 3051^2 + 3450^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21211101 is a prime.

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

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211109) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 31516 + ... + 32181.

Almost surely, 2^21211101 is an apocalyptic number.

It is an amenable number.

21211101 is a deficient number, since it is larger than the sum of its proper divisors (10255711).

21211101 is a wasteful number, since it uses less digits than its factorization.

21211101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63740 (or 63737 counting only the distinct ones).

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

The square root of 21211101 is about 4605.5511070881. The cubic root of 21211101 is about 276.8138000640.

Adding to 21211101 its reverse (10111212), we get a palindrome (31322313).

It can be divided in two parts, 21211 and 101, that added together give a palindrome (21312).

The spelling of 21211101 in words is "twenty-one million, two hundred eleven thousand, one hundred one".