21505266750517 has 32 divisors (see below), whose sum is σ = 23839122751488. Its totient is φ = 19397440062000.

The previous prime is 21505266750491. The next prime is 21505266750523. The reversal of 21505266750517 is 71505766250512.

It is a happy number.

It is not a de Polignac number, because 21505266750517 - 2¹⁹ = 21505266226229 is a prime.

It is a Smith number, since the sum of its digits (52) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21505266750217) 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, 1585109068 + ... + 1585122634.

It is an arithmetic number, because the mean of its divisors is an integer number (744972585984).

Almost surely, 2^{21505266750517} is an apocalyptic number.

It is an amenable number.

21505266750517 is a deficient number, since it is larger than the sum of its proper divisors (2333856000971).

21505266750517 is a wasteful number, since it uses less digits than its factorization.

21505266750517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22822 (or 22800 counting only the distinct ones).

The product of its (nonzero) digits is 4410000, while the sum is 52.

The spelling of 21505266750517 in words is "twenty-one trillion, five hundred five billion, two hundred sixty-six million, seven hundred fifty thousand, five hundred seventeen".