1666821215351 has 8 divisors (see below), whose sum is σ = 1671708741120. Its totient is φ = 1661939556088.

The previous prime is 1666821215341. The next prime is 1666821215359. The reversal of 1666821215351 is 1535121286661.

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 1666821215351 - 2¹⁴ = 1666821198967 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1666821215296 and 1666821215305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666821215359) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 897221 + ... + 2034366.

It is an arithmetic number, because the mean of its divisors is an integer number (208963592640).

Almost surely, 2^{1666821215351} is an apocalyptic number.

1666821215351 is a deficient number, since it is larger than the sum of its proper divisors (4887525769).

1666821215351 is a wasteful number, since it uses less digits than its factorization.

1666821215351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2933253.

The product of its digits is 518400, while the sum is 47.

The spelling of 1666821215351 in words is "one trillion, six hundred sixty-six billion, eight hundred twenty-one million, two hundred fifteen thousand, three hundred fifty-one".