21205165511052 has 36 divisors (see below), whose sum is σ = 53602094505960. Its totient is φ = 7068368940672.

The previous prime is 21205165511039. The next prime is 21205165511059. The reversal of 21205165511052 is 25011556150212.

21205165511052 is a `hidden beast` number, since 2 + 1 + 2 + 0 + 51 + 6 + 551 + 1 + 0 + 52 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21205165511052² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21205165510998 and 21205165511016.

It is not an unprimeable number, because it can be changed into a prime (21205165511059) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18914548 + ... + 20004260.

It is an arithmetic number, because the mean of its divisors is an integer number (1488947069610).

Almost surely, 2^{21205165511052} is an apocalyptic number.

It is an amenable number.

21205165511052 is an abundant number, since it is smaller than the sum of its proper divisors (32396928994908).

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

21205165511052 is a wasteful number, since it uses less digits than its factorization.

21205165511052 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1630262 (or 1630257 counting only the distinct ones).

The product of its (nonzero) digits is 30000, while the sum is 36.

The spelling of 21205165511052 in words is "twenty-one trillion, two hundred five billion, one hundred sixty-five million, five hundred eleven thousand, fifty-two".