21205717833 has 16 divisors (see below), whose sum is σ = 29051231040. Its totient is φ = 13749011136.

The previous prime is 21205717831. The next prime is 21205717843. The reversal of 21205717833 is 33871750212.

It is not a de Polignac number, because 21205717833 - 2¹ = 21205717831 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21205717791 and 21205717800.

It is not an unprimeable number, because it can be changed into a prime (21205717831) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 218791 + ... + 300467.

It is an arithmetic number, because the mean of its divisors is an integer number (1815701940).

Almost surely, 2^21205717833 is an apocalyptic number.

It is an amenable number.

21205717833 is a deficient number, since it is larger than the sum of its proper divisors (7845513207).

21205717833 is a wasteful number, since it uses less digits than its factorization.

21205717833 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84056.

The product of its (nonzero) digits is 70560, while the sum is 39.

The spelling of 21205717833 in words is "twenty-one billion, two hundred five million, seven hundred seventeen thousand, eight hundred thirty-three".