21335212566 has 40 divisors (see below), whose sum is σ = 47872167024. Its totient is φ = 7101995760.

The previous prime is 21335212559. The next prime is 21335212567. The reversal of 21335212566 is 66521253312.

21335212566 is a `hidden beast` number, since 2 + 1 + 33 + 52 + 12 + 566 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21335212566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21335212567) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 28911 + ... + 208581.

Almost surely, 2^21335212566 is an apocalyptic number.

21335212566 is an abundant number, since it is smaller than the sum of its proper divisors (26536954458).

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

21335212566 is a wasteful number, since it uses less digits than its factorization.

21335212566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180418 (or 180409 counting only the distinct ones).

The product of its digits is 64800, while the sum is 36.

Adding to 21335212566 its reverse (66521253312), we get a palindrome (87856465878).

The spelling of 21335212566 in words is "twenty-one billion, three hundred thirty-five million, two hundred twelve thousand, five hundred sixty-six".