21505166611650 has 72 divisors (see below), whose sum is σ = 58756489187760. Its totient is φ = 5637512596320.

The previous prime is 21505166611633. The next prime is 21505166611651. The reversal of 21505166611650 is 5611666150512.

21505166611650 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 21505166611596 and 21505166611605.

It is not an unprimeable number, because it can be changed into a prime (21505166611651) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 404967172 + ... + 405020271.

It is an arithmetic number, because the mean of its divisors is an integer number (816062349830).

Almost surely, 2^{21505166611650} is an apocalyptic number.

21505166611650 is an abundant number, since it is smaller than the sum of its proper divisors (37251322576110).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21505166611650 is a wasteful number, since it uses less digits than its factorization.

21505166611650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 809987520 (or 809987512 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 45.

The spelling of 21505166611650 in words is "twenty-one trillion, five hundred five billion, one hundred sixty-six million, six hundred eleven thousand, six hundred fifty".