21115505 has 8 divisors (see below), whose sum is σ = 25401600. Its totient is φ = 16850416.

The previous prime is 21115453. The next prime is 21115511. The reversal of 21115505 is 50551112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21115505 - 2⁸ = 21115249 is a prime.

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, 2945 + ... + 7134.

It is an arithmetic number, because the mean of its divisors is an integer number (3175200).

Almost surely, 2^21115505 is an apocalyptic number.

It is an amenable number.

21115505 is a deficient number, since it is larger than the sum of its proper divisors (4286095).

21115505 is a wasteful number, since it uses less digits than its factorization.

21115505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10503.

The product of its (nonzero) digits is 250, while the sum is 20.

The square root of 21115505 is about 4595.1610417917. The cubic root of 21115505 is about 276.3973177381.

Adding to 21115505 its reverse (50551112), we get a palindrome (71666617).

The spelling of 21115505 in words is "twenty-one million, one hundred fifteen thousand, five hundred five".