21323515 has 8 divisors (see below), whose sum is σ = 25638768. Its totient is φ = 17025120.

The previous prime is 21323513. The next prime is 21323521. The reversal of 21323515 is 51532312.

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

It is not a de Polignac number, because 21323515 - 2¹ = 21323513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21323513) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1237 + ... + 6646.

It is an arithmetic number, because the mean of its divisors is an integer number (3204846).

Almost surely, 2^21323515 is an apocalyptic number.

21323515 is a deficient number, since it is larger than the sum of its proper divisors (4315253).

21323515 is an equidigital number, since it uses as much as digits as its factorization.

21323515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8429.

The product of its digits is 900, while the sum is 22.

The square root of 21323515 is about 4617.7391654358. The cubic root of 21323515 is about 277.3019553856.

Adding to 21323515 its reverse (51532312), we get a palindrome (72855827).

The spelling of 21323515 in words is "twenty-one million, three hundred twenty-three thousand, five hundred fifteen".