21457315 has 32 divisors (see below), whose sum is σ = 30373056. Its totient is φ = 14376960.

The previous prime is 21457313. The next prime is 21457339. The reversal of 21457315 is 51375412.

It is a happy number.

It is not a de Polignac number, because 21457315 - 2¹ = 21457313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21457313) 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, 49339 + ... + 49771.

It is an arithmetic number, because the mean of its divisors is an integer number (949158).

Almost surely, 2^21457315 is an apocalyptic number.

21457315 is a deficient number, since it is larger than the sum of its proper divisors (8915741).

21457315 is a wasteful number, since it uses less digits than its factorization.

21457315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 519.

The product of its digits is 4200, while the sum is 28.

The square root of 21457315 is about 4632.2041189913. The cubic root of 21457315 is about 277.8807478103.

The spelling of 21457315 in words is "twenty-one million, four hundred fifty-seven thousand, three hundred fifteen".