21502355550523 has 4 divisors (see below), whose sum is σ = 21634271842408. Its totient is φ = 21370439258640.

The previous prime is 21502355550517. The next prime is 21502355550589. The reversal of 21502355550523 is 32505555320512.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21502355550523 is a prime.

It is a super-2 number, since 2×21502355550523² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21502355550523.

It is not an unprimeable number, because it can be changed into a prime (21502355550503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65958145698 + ... + 65958146023.

It is an arithmetic number, because the mean of its divisors is an integer number (5408567960602).

Almost surely, 2^{21502355550523} is an apocalyptic number.

21502355550523 is a deficient number, since it is larger than the sum of its proper divisors (131916291885).

21502355550523 is a wasteful number, since it uses less digits than its factorization.

21502355550523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131916291884.

The product of its (nonzero) digits is 1125000, while the sum is 43.

The spelling of 21502355550523 in words is "twenty-one trillion, five hundred two billion, three hundred fifty-five million, five hundred fifty thousand, five hundred twenty-three".