21004838 has 4 divisors (see below), whose sum is σ = 31507260. Its totient is φ = 10502418.

The previous prime is 21004831. The next prime is 21004847. The reversal of 21004838 is 83840012.

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

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5251208 + ... + 5251211.

It is an arithmetic number, because the mean of its divisors is an integer number (7876815).

Almost surely, 2^21004838 is an apocalyptic number.

21004838 is a deficient number, since it is larger than the sum of its proper divisors (10502422).

21004838 is a wasteful number, since it uses less digits than its factorization.

21004838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10502421.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21004838 is about 4583.1035336331. The cubic root of 21004838 is about 275.9136027973.

The spelling of 21004838 in words is "twenty-one million, four thousand, eight hundred thirty-eight".