21105315 has 48 divisors (see below), whose sum is σ = 45616896. Its totient is φ = 8769600.

The previous prime is 21105307. The next prime is 21105341. The reversal of 21105315 is 51350112.

It is not a de Polignac number, because 21105315 - 2³ = 21105307 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 420 + ... + 6510.

It is an arithmetic number, because the mean of its divisors is an integer number (950352).

Almost surely, 2^21105315 is an apocalyptic number.

21105315 is an abundant number, since it is smaller than the sum of its proper divisors (24511581).

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

21105315 is a wasteful number, since it uses less digits than its factorization.

21105315 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6120 (or 6117 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21105315 is about 4594.0521329214. The cubic root of 21105315 is about 276.3528489642.

Adding to 21105315 its reverse (51350112), we get a palindrome (72455427).

The spelling of 21105315 in words is "twenty-one million, one hundred five thousand, three hundred fifteen".