21214615 has 4 divisors (see below), whose sum is σ = 25457544. Its totient is φ = 16971688.

The previous prime is 21214577. The next prime is 21214619. The reversal of 21214615 is 51641212.

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 21214615 - 2²¹ = 19117463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21214619) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2121457 + ... + 2121466.

It is an arithmetic number, because the mean of its divisors is an integer number (6364386).

Almost surely, 2^21214615 is an apocalyptic number.

21214615 is a deficient number, since it is larger than the sum of its proper divisors (4242929).

21214615 is an equidigital number, since it uses as much as digits as its factorization.

21214615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4242928.

The product of its digits is 480, while the sum is 22.

The square root of 21214615 is about 4605.9325874355. The cubic root of 21214615 is about 276.8290856132.

Adding to 21214615 its reverse (51641212), we get a palindrome (72855827).

The spelling of 21214615 in words is "twenty-one million, two hundred fourteen thousand, six hundred fifteen".