1666006501 has 2 divisors, whose sum is σ = 1666006502. Its totient is φ = 1666006500.

The previous prime is 1666006499. The next prime is 1666006513. The reversal of 1666006501 is 1056006661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1613950276 + 52056225 = 40174^2 + 7215^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666006501 - 2¹ = 1666006499 is a prime.

It is a super-2 number, since 2×1666006501² = 5551155322748526002, which contains 22 as substring.

Together with 1666006499, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666006561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833003250 + 833003251.

It is an arithmetic number, because the mean of its divisors is an integer number (833003251).

Almost surely, 2^1666006501 is an apocalyptic number.

It is an amenable number.

1666006501 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666006501 is an equidigital number, since it uses as much as digits as its factorization.

1666006501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 31.

The square root of 1666006501 is about 40816.7429004324. The cubic root of 1666006501 is about 1185.4745382340.

The spelling of 1666006501 in words is "one billion, six hundred sixty-six million, six thousand, five hundred one".