21166049 has 4 divisors (see below), whose sum is σ = 22086336. Its totient is φ = 20245764.

The previous prime is 21166009. The next prime is 21166051. The reversal of 21166049 is 94066112.

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 21166049 - 2²⁰ = 20117473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21166009) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 460109 + ... + 460154.

It is an arithmetic number, because the mean of its divisors is an integer number (5521584).

Almost surely, 2^21166049 is an apocalyptic number.

It is an amenable number.

21166049 is a deficient number, since it is larger than the sum of its proper divisors (920287).

21166049 is an equidigital number, since it uses as much as digits as its factorization.

21166049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 920286.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21166049 is about 4600.6574530169. The cubic root of 21166049 is about 276.6176786218.

The spelling of 21166049 in words is "twenty-one million, one hundred sixty-six thousand, forty-nine".