21070215 has 24 divisors (see below), whose sum is σ = 37374480. Its totient is φ = 10975104.

The previous prime is 21070201. The next prime is 21070237. The reversal of 21070215 is 51207012.

It is not a de Polignac number, because 21070215 - 2⁹ = 21069703 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3510 + ... + 7379.

It is an arithmetic number, because the mean of its divisors is an integer number (1557270).

Almost surely, 2^21070215 is an apocalyptic number.

21070215 is a deficient number, since it is larger than the sum of its proper divisors (16304265).

21070215 is a wasteful number, since it uses less digits than its factorization.

21070215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10943 (or 10940 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21070215 is about 4590.2303863750. The cubic root of 21070215 is about 276.1995642382.

Adding to 21070215 its reverse (51207012), we get a palindrome (72277227).

The spelling of 21070215 in words is "twenty-one million, seventy thousand, two hundred fifteen".