21252552320666 has 16 divisors (see below), whose sum is σ = 33265667075904. Its totient is φ = 10164018922464.

The previous prime is 21252552320651. The next prime is 21252552320723. The reversal of 21252552320666 is 66602325525212.

It is a self number, because there is not a number n which added to its sum of digits gives 21252552320666.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3638891 + ... + 7466366.

It is an arithmetic number, because the mean of its divisors is an integer number (2079104192244).

Almost surely, 2^{21252552320666} is an apocalyptic number.

21252552320666 is a deficient number, since it is larger than the sum of its proper divisors (12013114755238).

21252552320666 is a wasteful number, since it uses less digits than its factorization.

21252552320666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11146885.

The product of its (nonzero) digits is 2592000, while the sum is 47.

Adding to 21252552320666 its reverse (66602325525212), we get a palindrome (87854877845878).

The spelling of 21252552320666 in words is "twenty-one trillion, two hundred fifty-two billion, five hundred fifty-two million, three hundred twenty thousand, six hundred sixty-six".