21052215 has 12 divisors (see below), whose sum is σ = 36490584. Its totient is φ = 11227824.

The previous prime is 21052177. The next prime is 21052217. The reversal of 21052215 is 51225012.

It is not a de Polignac number, because 21052215 - 2⁹ = 21051703 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052217) 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 11 ways as a sum of consecutive naturals, for example, 233869 + ... + 233958.

It is an arithmetic number, because the mean of its divisors is an integer number (3040882).

Almost surely, 2^21052215 is an apocalyptic number.

21052215 is a deficient number, since it is larger than the sum of its proper divisors (15438369).

21052215 is a wasteful number, since it uses less digits than its factorization.

21052215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 467838 (or 467835 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21052215 is about 4588.2692815483. The cubic root of 21052215 is about 276.1208906453.

Adding to 21052215 its reverse (51225012), we get a palindrome (72277227).

It can be divided in two parts, 210 and 52215, that added together give a palindrome (52425).

The spelling of 21052215 in words is "twenty-one million, fifty-two thousand, two hundred fifteen".