1666015961 has 4 divisors (see below), whose sum is σ = 1666099152. Its totient is φ = 1665932772.

The previous prime is 1666015943. The next prime is 1666016021. The reversal of 1666015961 is 1695106661.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 1666015961 - 2²² = 1661821657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1666005961) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8786 + ... + 58388.

It is an arithmetic number, because the mean of its divisors is an integer number (416524788).

Almost surely, 2^1666015961 is an apocalyptic number.

It is an amenable number.

1666015961 is a deficient number, since it is larger than the sum of its proper divisors (83191).

1666015961 is an equidigital number, since it uses as much as digits as its factorization.

1666015961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83190.

The product of its (nonzero) digits is 58320, while the sum is 41.

The square root of 1666015961 is about 40816.8587840858. The cubic root of 1666015961 is about 1185.4767820364.

The spelling of 1666015961 in words is "one billion, six hundred sixty-six million, fifteen thousand, nine hundred sixty-one".