21381183 has 6 divisors (see below), whose sum is σ = 30883944. Its totient is φ = 14254116.

The previous prime is 21381181. The next prime is 21381203. The reversal of 21381183 is 38118312.

It is not a de Polignac number, because 21381183 - 2¹ = 21381181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21381181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1187835 + ... + 1187852.

It is an arithmetic number, because the mean of its divisors is an integer number (5147324).

Almost surely, 2^21381183 is an apocalyptic number.

21381183 is a deficient number, since it is larger than the sum of its proper divisors (9502761).

21381183 is a wasteful number, since it uses less digits than its factorization.

21381183 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2375693 (or 2375690 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 21381183 is about 4623.9791305757. The cubic root of 21381183 is about 277.5517118141.

Adding to 21381183 its reverse (38118312), we get a palindrome (59499495).

It can be divided in two parts, 2138 and 1183, that added together give a triangular number (3321 = T₈₁).

The spelling of 21381183 in words is "twenty-one million, three hundred eighty-one thousand, one hundred eighty-three".