21285115 has 4 divisors (see below), whose sum is σ = 25542144. Its totient is φ = 17028088.

The previous prime is 21285113. The next prime is 21285119. The reversal of 21285115 is 51158212.

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 21285115 - 2¹ = 21285113 is a prime.

It is a super-2 number, since 2×21285115² = 906112241126450, which contains 22 as substring.

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 21285115.

It is not an unprimeable number, because it can be changed into a prime (21285113) 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 3 ways as a sum of consecutive naturals, for example, 2128507 + ... + 2128516.

It is an arithmetic number, because the mean of its divisors is an integer number (6385536).

Almost surely, 2^21285115 is an apocalyptic number.

21285115 is a deficient number, since it is larger than the sum of its proper divisors (4257029).

21285115 is an equidigital number, since it uses as much as digits as its factorization.

21285115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4257028.

The product of its digits is 800, while the sum is 25.

The square root of 21285115 is about 4613.5794129938. The cubic root of 21285115 is about 277.1353975820.

The spelling of 21285115 in words is "twenty-one million, two hundred eighty-five thousand, one hundred fifteen".