21520315 has 8 divisors (see below), whose sum is σ = 25908768. Its totient is φ = 17160000.

The previous prime is 21520307. The next prime is 21520361. The reversal of 21520315 is 51302512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21520315 - 2³ = 21520307 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21520292 and 21520301.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5311 + ... + 8440.

It is an arithmetic number, because the mean of its divisors is an integer number (3238596).

Almost surely, 2^21520315 is an apocalyptic number.

21520315 is a deficient number, since it is larger than the sum of its proper divisors (4388453).

21520315 is a wasteful number, since it uses less digits than its factorization.

21520315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14069.

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

The square root of 21520315 is about 4638.9993533089. Note that the first 3 decimals coincide. The cubic root of 21520315 is about 278.1524404184.

Adding to 21520315 its reverse (51302512), we get a palindrome (72822827).

The spelling of 21520315 in words is "twenty-one million, five hundred twenty thousand, three hundred fifteen".