21231101 has 4 divisors (see below), whose sum is σ = 21522012. Its totient is φ = 20940192.

The previous prime is 21231029. The next prime is 21231107. The reversal of 21231101 is 10113212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14830201 + 6400900 = 3851^2 + 2530^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231101 - 2¹⁸ = 20968957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231107) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 145346 + ... + 145491.

It is an arithmetic number, because the mean of its divisors is an integer number (5380503).

Almost surely, 2^21231101 is an apocalyptic number.

It is an amenable number.

21231101 is a deficient number, since it is larger than the sum of its proper divisors (290911).

21231101 is an equidigital number, since it uses as much as digits as its factorization.

21231101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290910.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21231101 is about 4607.7218883088. The cubic root of 21231101 is about 276.9007755406.

Adding to 21231101 its reverse (10113212), we get a palindrome (31344313).

It can be divided in two parts, 212 and 31101, that added together give a palindrome (31313).

The spelling of 21231101 in words is "twenty-one million, two hundred thirty-one thousand, one hundred one".