21121235215 has 8 divisors (see below), whose sum is σ = 26030495520. Its totient is φ = 16440312672.

The previous prime is 21121235189. The next prime is 21121235227. The reversal of 21121235215 is 51253212112.

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 21121235215 - 2¹⁹ = 21120710927 is a prime.

It is a super-2 number, since 2×21121235215² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21121235215.

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, 57084235 + ... + 57084604.

It is an arithmetic number, because the mean of its divisors is an integer number (3253811940).

Almost surely, 2^21121235215 is an apocalyptic number.

21121235215 is a deficient number, since it is larger than the sum of its proper divisors (4909260305).

21121235215 is a wasteful number, since it uses less digits than its factorization.

21121235215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 114168881.

The product of its digits is 1200, while the sum is 25.

Adding to 21121235215 its reverse (51253212112), we get a palindrome (72374447327).

The spelling of 21121235215 in words is "twenty-one billion, one hundred twenty-one million, two hundred thirty-five thousand, two hundred fifteen".