21138783 has 4 divisors (see below), whose sum is σ = 28185048. Its totient is φ = 14092520.

The previous prime is 21138781. The next prime is 21138791. The reversal of 21138783 is 38783112.

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

It is a cyclic number.

It is not a de Polignac number, because 21138783 - 2¹ = 21138781 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138781) 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 3 ways as a sum of consecutive naturals, for example, 3523128 + ... + 3523133.

It is an arithmetic number, because the mean of its divisors is an integer number (7046262).

Almost surely, 2^21138783 is an apocalyptic number.

21138783 is a deficient number, since it is larger than the sum of its proper divisors (7046265).

21138783 is an equidigital number, since it uses as much as digits as its factorization.

21138783 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7046264.

The product of its digits is 8064, while the sum is 33.

The square root of 21138783 is about 4597.6932259558. The cubic root of 21138783 is about 276.4988484049.

The spelling of 21138783 in words is "twenty-one million, one hundred thirty-eight thousand, seven hundred eighty-three".