21351166645505 has 8 divisors (see below), whose sum is σ = 25728602486400. Its totient is φ = 17009464975216.

The previous prime is 21351166645493. The next prime is 21351166645513. The reversal of 21351166645505 is 50554666115312.

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 21351166645505 - 2⁴ = 21351166645489 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8933541335 + ... + 8933543724.

It is an arithmetic number, because the mean of its divisors is an integer number (3216075310800).

Almost surely, 2^{21351166645505} is an apocalyptic number.

It is an amenable number.

21351166645505 is a deficient number, since it is larger than the sum of its proper divisors (4377435840895).

21351166645505 is a wasteful number, since it uses less digits than its factorization.

21351166645505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17867085303.

The product of its (nonzero) digits is 3240000, while the sum is 50.

The spelling of 21351166645505 in words is "twenty-one trillion, three hundred fifty-one billion, one hundred sixty-six million, six hundred forty-five thousand, five hundred five".