21020215 has 8 divisors (see below), whose sum is σ = 26094240. Its totient is φ = 16236192.

The previous prime is 21020161. The next prime is 21020227. The reversal of 21020215 is 51202012.

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

It is a cyclic number.

It is not a de Polignac number, because 21020215 - 2¹¹ = 21018167 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020195 and 21020204.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 72339 + ... + 72628.

It is an arithmetic number, because the mean of its divisors is an integer number (3261780).

Almost surely, 2^21020215 is an apocalyptic number.

21020215 is a deficient number, since it is larger than the sum of its proper divisors (5074025).

21020215 is a wasteful number, since it uses less digits than its factorization.

21020215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145001.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21020215 is about 4584.7808017396. The cubic root of 21020215 is about 275.9809156797.

Adding to 21020215 its reverse (51202012), we get a palindrome (72222227).

The spelling of 21020215 in words is "twenty-one million, twenty thousand, two hundred fifteen".