21005315235 has 24 divisors (see below), whose sum is σ = 37664705520. Its totient is φ = 10816529472.

The previous prime is 21005315213. The next prime is 21005315249. The reversal of 21005315235 is 53251350012.

It is a happy number.

21005315235 is a `hidden beast` number, since 2 + 100 + 5 + 31 + 523 + 5 = 666.

It is not a de Polignac number, because 21005315235 - 2⁶ = 21005315171 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21005315199 and 21005315208.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8046709 + ... + 8049318.

It is an arithmetic number, because the mean of its divisors is an integer number (1569362730).

Almost surely, 2^21005315235 is an apocalyptic number.

21005315235 is a deficient number, since it is larger than the sum of its proper divisors (16659390285).

21005315235 is a wasteful number, since it uses less digits than its factorization.

21005315235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16096067 (or 16096064 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 27.

Adding to 21005315235 its reverse (53251350012), we get a palindrome (74256665247).

The spelling of 21005315235 in words is "twenty-one billion, five million, three hundred fifteen thousand, two hundred thirty-five".