21133253665 has 16 divisors (see below), whose sum is σ = 26792570880. Its totient is φ = 15976300480.

The previous prime is 21133253653. The next prime is 21133253681. The reversal of 21133253665 is 56635233112.

It is not a de Polignac number, because 21133253665 - 2¹³ = 21133245473 is a prime.

It is a super-3 number, since 3×21133253665³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1543681 + ... + 1557310.

It is an arithmetic number, because the mean of its divisors is an integer number (1674535680).

Almost surely, 2^21133253665 is an apocalyptic number.

It is an amenable number.

21133253665 is a deficient number, since it is larger than the sum of its proper divisors (5659317215).

21133253665 is a wasteful number, since it uses less digits than its factorization.

21133253665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3101072.

The product of its digits is 97200, while the sum is 37.

Adding to 21133253665 its reverse (56635233112), we get a palindrome (77768486777).

The spelling of 21133253665 in words is "twenty-one billion, one hundred thirty-three million, two hundred fifty-three thousand, six hundred sixty-five".