21167749 has 4 divisors (see below), whose sum is σ = 21210336. Its totient is φ = 21125164.

The previous prime is 21167747. The next prime is 21167789. The reversal of 21167749 is 94776112.

21167749 is nontrivially palindromic in base 2.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21167749 - 2¹ = 21167747 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 (21167747) 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, 20539 + ... + 21544.

It is an arithmetic number, because the mean of its divisors is an integer number (5302584).

Almost surely, 2^21167749 is an apocalyptic number.

It is an amenable number.

21167749 is a deficient number, since it is larger than the sum of its proper divisors (42587).

21167749 is an equidigital number, since it uses as much as digits as its factorization.

21167749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42586.

The product of its digits is 21168, while the sum is 37.

The square root of 21167749 is about 4600.8422055098. The cubic root of 21167749 is about 276.6250841523.

The spelling of 21167749 in words is "twenty-one million, one hundred sixty-seven thousand, seven hundred forty-nine".