21305039611 has 4 divisors (see below), whose sum is σ = 21500498800. Its totient is φ = 21109580424.

The previous prime is 21305039603. The next prime is 21305039629. The reversal of 21305039611 is 11693050312.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21305039611 - 2³ = 21305039603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21305039411) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97729431 + ... + 97729648.

It is an arithmetic number, because the mean of its divisors is an integer number (5375124700).

Almost surely, 2^21305039611 is an apocalyptic number.

21305039611 is a deficient number, since it is larger than the sum of its proper divisors (195459189).

21305039611 is a wasteful number, since it uses less digits than its factorization.

21305039611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195459188.

The product of its (nonzero) digits is 4860, while the sum is 31.

Adding to 21305039611 its reverse (11693050312), we get a palindrome (32998089923).

The spelling of 21305039611 in words is "twenty-one billion, three hundred five million, thirty-nine thousand, six hundred eleven".