21004863 has 16 divisors (see below), whose sum is σ = 31380096. Its totient is φ = 12385440.

The previous prime is 21004847. The next prime is 21004883. The reversal of 21004863 is 36840012.

It is a happy number.

It is not a de Polignac number, because 21004863 - 2⁴ = 21004847 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004813) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7381 + ... + 9822.

It is an arithmetic number, because the mean of its divisors is an integer number (1961256).

Almost surely, 2^21004863 is an apocalyptic number.

21004863 is a deficient number, since it is larger than the sum of its proper divisors (10375233).

21004863 is a wasteful number, since it uses less digits than its factorization.

21004863 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17254.

The product of its (nonzero) digits is 1152, while the sum is 24.

The square root of 21004863 is about 4583.1062610417. The cubic root of 21004863 is about 275.9137122615.

Adding to 21004863 its reverse (36840012), we get a palindrome (57844875).

The spelling of 21004863 in words is "twenty-one million, four thousand, eight hundred sixty-three".