21916015 has 8 divisors (see below), whose sum is σ = 28690128. Its totient is φ = 15938880.

The previous prime is 21916003. The next prime is 21916021. The reversal of 21916015 is 51061912.

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

It is not a de Polignac number, because 21916015 - 2¹⁷ = 21784943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 199182 + ... + 199291.

It is an arithmetic number, because the mean of its divisors is an integer number (3586266).

Almost surely, 2^21916015 is an apocalyptic number.

21916015 is a deficient number, since it is larger than the sum of its proper divisors (6774113).

21916015 is a wasteful number, since it uses less digits than its factorization.

21916015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398489.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21916015 is about 4681.4543680356. The cubic root of 21916015 is about 279.8469188740.

Adding to 21916015 its reverse (51061912), we get a palindrome (72977927).

The spelling of 21916015 in words is "twenty-one million, nine hundred sixteen thousand, fifteen".