21214915 has 4 divisors (see below), whose sum is σ = 25457904. Its totient is φ = 16971928.

The previous prime is 21214913. The next prime is 21214927. The reversal of 21214915 is 51941212.

It is a happy number.

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 21214915 - 2¹ = 21214913 is a prime.

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 21214915.

It is not an unprimeable number, because it can be changed into a prime (21214913) 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, 2121487 + ... + 2121496.

It is an arithmetic number, because the mean of its divisors is an integer number (6364476).

Almost surely, 2^21214915 is an apocalyptic number.

21214915 is a deficient number, since it is larger than the sum of its proper divisors (4242989).

21214915 is an equidigital number, since it uses as much as digits as its factorization.

21214915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4242988.

The product of its digits is 720, while the sum is 25.

The square root of 21214915 is about 4605.9651540150. The cubic root of 21214915 is about 276.8303905050.

The spelling of 21214915 in words is "twenty-one million, two hundred fourteen thousand, nine hundred fifteen".