21004910 has 16 divisors (see below), whose sum is σ = 37950336. Its totient is φ = 8370528.

The previous prime is 21004909. The next prime is 21004913. The reversal of 21004910 is 1940012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004913) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1022 + ... + 6561.

It is an arithmetic number, because the mean of its divisors is an integer number (2371896).

Almost surely, 2^21004910 is an apocalyptic number.

21004910 is a deficient number, since it is larger than the sum of its proper divisors (16945426).

21004910 is a wasteful number, since it uses less digits than its factorization.

21004910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7867.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21004910 is about 4583.1113885656. Note that the first 3 decimals coincide. The cubic root of 21004910 is about 275.9139180541.

Adding to 21004910 its reverse (1940012), we get a palindrome (22944922).

The spelling of 21004910 in words is "twenty-one million, four thousand, nine hundred ten".