21304172 has 6 divisors (see below), whose sum is σ = 37282308. Its totient is φ = 10652084.

The previous prime is 21304147. The next prime is 21304219. The reversal of 21304172 is 27140312.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2663018 + ... + 2663025.

It is an arithmetic number, because the mean of its divisors is an integer number (6213718).

Almost surely, 2^21304172 is an apocalyptic number.

It is an amenable number.

21304172 is a deficient number, since it is larger than the sum of its proper divisors (15978136).

21304172 is a wasteful number, since it uses less digits than its factorization.

21304172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5326047 (or 5326045 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21304172 is about 4615.6442670553. The cubic root of 21304172 is about 277.2180812459.

Adding to 21304172 its reverse (27140312), we get a palindrome (48444484).

The spelling of 21304172 in words is "twenty-one million, three hundred four thousand, one hundred seventy-two".