21004210 has 16 divisors (see below), whose sum is σ = 38687616. Its totient is φ = 8206128.

The previous prime is 21004189. The next prime is 21004211. The reversal of 21004210 is 1240012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is not an unprimeable number, because it can be changed into a prime (21004211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23994 + ... + 24853.

It is an arithmetic number, because the mean of its divisors is an integer number (2417976).

Almost surely, 2^21004210 is an apocalyptic number.

21004210 is a deficient number, since it is larger than the sum of its proper divisors (17683406).

21004210 is a wasteful number, since it uses less digits than its factorization.

21004210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48897.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21004210 is about 4583.0350205950. The cubic root of 21004210 is about 275.9108530265.

Adding to 21004210 its reverse (1240012), we get a palindrome (22244222).

The spelling of 21004210 in words is "twenty-one million, four thousand, two hundred ten".