21217806041 has 4 divisors (see below), whose sum is σ = 21228694500. Its totient is φ = 21206917584.

The previous prime is 21217805971. The next prime is 21217806073. The reversal of 21217806041 is 14060871212.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9773299600 + 11444506441 = 98860^2 + 106979^2 .

It is a cyclic number.

It is not a de Polignac number, because 21217806041 - 2¹⁰ = 21217805017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21217805989 and 21217806007.

It is not an unprimeable number, because it can be changed into a prime (21217806241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5441306 + ... + 5445203.

It is an arithmetic number, because the mean of its divisors is an integer number (5307173625).

Almost surely, 2^21217806041 is an apocalyptic number.

It is an amenable number.

21217806041 is a deficient number, since it is larger than the sum of its proper divisors (10888459).

21217806041 is a wasteful number, since it uses less digits than its factorization.

21217806041 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10888458.

The product of its (nonzero) digits is 5376, while the sum is 32.

The spelling of 21217806041 in words is "twenty-one billion, two hundred seventeen million, eight hundred six thousand, forty-one".