21315250 has 64 divisors (see below), whose sum is σ = 45556992. Its totient is φ = 7392000.

The previous prime is 21315247. The next prime is 21315251. The reversal of 21315250 is 5251312.

It is not an unprimeable number, because it can be changed into a prime (21315251) 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 31 ways as a sum of consecutive naturals, for example, 63082 + ... + 63418.

It is an arithmetic number, because the mean of its divisors is an integer number (711828).

Almost surely, 2^21315250 is an apocalyptic number.

21315250 is an abundant number, since it is smaller than the sum of its proper divisors (24241742).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21315250 is a wasteful number, since it uses less digits than its factorization.

21315250 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388 (or 378 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 21315250 is about 4616.8441602463. The cubic root of 21315250 is about 277.2661233188.

Adding to 21315250 its reverse (5251312), we get a palindrome (26566562).

It can be divided in two parts, 2131 and 5250, that added together give a triangular number (7381 = T₁₂₁).

The spelling of 21315250 in words is "twenty-one million, three hundred fifteen thousand, two hundred fifty".