21115515506366 has 16 divisors (see below), whose sum is σ = 32462187413040. Its totient is φ = 10295046611520.

The previous prime is 21115515506359. The next prime is 21115515506369. The reversal of 21115515506366 is 66360551551112.

It is a self number, because there is not a number n which added to its sum of digits gives 21115515506366.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115515506369) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64897421 + ... + 65221976.

It is an arithmetic number, because the mean of its divisors is an integer number (2028886713315).

Almost surely, 2^{21115515506366} is an apocalyptic number.

21115515506366 is a deficient number, since it is larger than the sum of its proper divisors (11346671906674).

21115515506366 is a wasteful number, since it uses less digits than its factorization.

21115515506366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130121419.

The product of its (nonzero) digits is 810000, while the sum is 47.

The spelling of 21115515506366 in words is "twenty-one trillion, one hundred fifteen billion, five hundred fifteen million, five hundred six thousand, three hundred sixty-six".