21020315 has 4 divisors (see below), whose sum is σ = 25224384. Its totient is φ = 16816248.

The previous prime is 21020303. The next prime is 21020339. The reversal of 21020315 is 51302012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21020315 - 2⁴ = 21020299 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21020315.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2102027 + ... + 2102036.

It is an arithmetic number, because the mean of its divisors is an integer number (6306096).

Almost surely, 2^21020315 is an apocalyptic number.

21020315 is a deficient number, since it is larger than the sum of its proper divisors (4204069).

21020315 is an equidigital number, since it uses as much as digits as its factorization.

21020315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4204068.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21020315 is about 4584.7917073734. The cubic root of 21020315 is about 275.9813533226.

Adding to 21020315 its reverse (51302012), we get a palindrome (72322327).

The spelling of 21020315 in words is "twenty-one million, twenty thousand, three hundred fifteen".