166661500001551 has 2 divisors, whose sum is σ = 166661500001552. Its totient is φ = 166661500001550.

The previous prime is 166661500001543. The next prime is 166661500001681. The reversal of 166661500001551 is 155100005166661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 166661500001551 - 2³ = 166661500001543 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 166661500001498 and 166661500001507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (166661510001551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83330750000775 + 83330750000776.

It is an arithmetic number, because the mean of its divisors is an integer number (83330750000776).

Almost surely, 2^{166661500001551} is an apocalyptic number.

166661500001551 is a deficient number, since it is larger than the sum of its proper divisors (1).

166661500001551 is an equidigital number, since it uses as much as digits as its factorization.

166661500001551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 162000, while the sum is 43.

The spelling of 166661500001551 in words is "one hundred sixty-six trillion, six hundred sixty-one billion, five hundred million, one thousand, five hundred fifty-one".