21661042630017 has 32 divisors (see below), whose sum is σ = 33567630796800. Its totient is φ = 12167626768128.

The previous prime is 21661042629943. The next prime is 21661042630021. The reversal of 21661042630017 is 71003624016612.

It is a happy number.

It is not a de Polignac number, because 21661042630017 - 2¹⁶ = 21661042564481 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21661042630037) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 51679353 + ... + 52096809.

It is an arithmetic number, because the mean of its divisors is an integer number (1048988462400).

Almost surely, 2^{21661042630017} is an apocalyptic number.

It is an amenable number.

21661042630017 is a deficient number, since it is larger than the sum of its proper divisors (11906588166783).

21661042630017 is a wasteful number, since it uses less digits than its factorization.

21661042630017 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459405.

The product of its (nonzero) digits is 72576, while the sum is 39.

Adding to 21661042630017 its reverse (71003624016612), we get a palindrome (92664666646629).

The spelling of 21661042630017 in words is "twenty-one trillion, six hundred sixty-one billion, forty-two million, six hundred thirty thousand, seventeen".