21184945 has 4 divisors (see below), whose sum is σ = 25421940. Its totient is φ = 16947952.

The previous prime is 21184903. The next prime is 21184951. The reversal of 21184945 is 54948112.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10764961 + 10419984 = 3281^2 + 3228^2 .

It is a cyclic number.

It is not a de Polignac number, because 21184945 - 2¹⁷ = 21053873 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21184945.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2118490 + ... + 2118499.

It is an arithmetic number, because the mean of its divisors is an integer number (6355485).

Almost surely, 2^21184945 is an apocalyptic number.

It is an amenable number.

21184945 is a deficient number, since it is larger than the sum of its proper divisors (4236995).

21184945 is an equidigital number, since it uses as much as digits as its factorization.

21184945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4236994.

The product of its digits is 11520, while the sum is 34.

The square root of 21184945 is about 4602.7106144097. The cubic root of 21184945 is about 276.6999709912.

The spelling of 21184945 in words is "twenty-one million, one hundred eighty-four thousand, nine hundred forty-five".