21004845 has 32 divisors (see below), whose sum is σ = 35164800. Its totient is φ = 10692864.

The previous prime is 21004831. The next prime is 21004847. The reversal of 21004845 is 54840012.

It is not a de Polignac number, because 21004845 - 2⁴ = 21004829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004847) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 47194 + ... + 47636.

It is an arithmetic number, because the mean of its divisors is an integer number (1098900).

Almost surely, 2^21004845 is an apocalyptic number.

It is an amenable number.

21004845 is a deficient number, since it is larger than the sum of its proper divisors (14159955).

21004845 is a wasteful number, since it uses less digits than its factorization.

21004845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 589.

The product of its (nonzero) digits is 1280, while the sum is 24.

The square root of 21004845 is about 4583.1042973077. The cubic root of 21004845 is about 275.9136334473.

Adding to 21004845 its reverse (54840012), we get a palindrome (75844857).

The spelling of 21004845 in words is "twenty-one million, four thousand, eight hundred forty-five".