21801135 has 16 divisors (see below), whose sum is σ = 35733600. Its totient is φ = 11343360.

The previous prime is 21801133. The next prime is 21801161. The reversal of 21801135 is 53110812.

It is not a de Polignac number, because 21801135 - 2¹ = 21801133 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21801133) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17110 + ... + 18339.

It is an arithmetic number, because the mean of its divisors is an integer number (2233350).

Almost surely, 2^21801135 is an apocalyptic number.

21801135 is a deficient number, since it is larger than the sum of its proper divisors (13932465).

21801135 is a wasteful number, since it uses less digits than its factorization.

21801135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35498.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 21801135 is about 4669.1685555353. The cubic root of 21801135 is about 279.3570921262.

Adding to 21801135 its reverse (53110812), we get a palindrome (74911947).

The spelling of 21801135 in words is "twenty-one million, eight hundred one thousand, one hundred thirty-five".