21517121822655 has 32 divisors (see below), whose sum is σ = 35012382451200. Its totient is φ = 11280818820992.

The previous prime is 21517121822639. The next prime is 21517121822723. The reversal of 21517121822655 is 55622812171512.

It is a cyclic number.

It is not a de Polignac number, because 21517121822655 - 2⁴ = 21517121822639 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21058657 + ... + 22056773.

It is an arithmetic number, because the mean of its divisors is an integer number (1094136951600).

Almost surely, 2^{21517121822655} is an apocalyptic number.

21517121822655 is a deficient number, since it is larger than the sum of its proper divisors (13495260628545).

21517121822655 is a wasteful number, since it uses less digits than its factorization.

21517121822655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022543.

The product of its digits is 672000, while the sum is 48.

The spelling of 21517121822655 in words is "twenty-one trillion, five hundred seventeen billion, one hundred twenty-one million, eight hundred twenty-two thousand, six hundred fifty-five".