21243115 has 16 divisors (see below), whose sum is σ = 27099360. Its totient is φ = 15930880.

The previous prime is 21243077. The next prime is 21243137. The reversal of 21243115 is 51134212.

It is not a de Polignac number, because 21243115 - 2¹³ = 21234923 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21243092 and 21243101.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41481 + ... + 41989.

It is an arithmetic number, because the mean of its divisors is an integer number (1693710).

Almost surely, 2^21243115 is an apocalyptic number.

21243115 is a deficient number, since it is larger than the sum of its proper divisors (5856245).

21243115 is a wasteful number, since it uses less digits than its factorization.

21243115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022.

The product of its digits is 240, while the sum is 19.

The square root of 21243115 is about 4609.0253850462. The cubic root of 21243115 is about 276.9529954518.

Adding to 21243115 its reverse (51134212), we get a palindrome (72377327).

The spelling of 21243115 in words is "twenty-one million, two hundred forty-three thousand, one hundred fifteen".