21205354011 has 16 divisors (see below), whose sum is σ = 28339808928. Its totient is φ = 14103936000.

The previous prime is 21205353991. The next prime is 21205354013. The reversal of 21205354011 is 11045350212.

It is a happy number.

It is not a de Polignac number, because 21205354011 - 2⁵ = 21205353979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21205354013) 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, 3330471 + ... + 3336831.

It is an arithmetic number, because the mean of its divisors is an integer number (1771238058).

Almost surely, 2^21205354011 is an apocalyptic number.

21205354011 is a deficient number, since it is larger than the sum of its proper divisors (7134454917).

21205354011 is a wasteful number, since it uses less digits than its factorization.

21205354011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8782.

The product of its (nonzero) digits is 1200, while the sum is 24.

The spelling of 21205354011 in words is "twenty-one billion, two hundred five million, three hundred fifty-four thousand, eleven".