21155356662065 has 8 divisors (see below), whose sum is σ = 25513997985600. Its totient is φ = 16839238668912.

The previous prime is 21155356662053. The next prime is 21155356662103. The reversal of 21155356662065 is 56026665355112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21155356662065 - 2¹⁰ = 21155356661041 is a prime.

It is a super-2 number, since 2×21155356662065² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21155356661998 and 21155356662016.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10630831499 + ... + 10630833488.

It is an arithmetic number, because the mean of its divisors is an integer number (3189249748200).

Almost surely, 2^{21155356662065} is an apocalyptic number.

It is an amenable number.

21155356662065 is a deficient number, since it is larger than the sum of its proper divisors (4358641323535).

21155356662065 is a wasteful number, since it uses less digits than its factorization.

21155356662065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21261665191.

The product of its (nonzero) digits is 9720000, while the sum is 53.

The spelling of 21155356662065 in words is "twenty-one trillion, one hundred fifty-five billion, three hundred fifty-six million, six hundred sixty-two thousand, sixty-five".