1666212061 has 4 divisors (see below), whose sum is σ = 1666696672. Its totient is φ = 1665727452.

The previous prime is 1666212059. The next prime is 1666212071. The reversal of 1666212061 is 1602126661.

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 an emirpimes, since its reverse is a distinct semiprime: 1602126661 = 7877 ⋅203393.

It is a cyclic number.

It is not a de Polignac number, because 1666212061 - 2¹ = 1666212059 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666212001) 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, 237111 + ... + 244036.

It is an arithmetic number, because the mean of its divisors is an integer number (416674168).

Almost surely, 2^1666212061 is an apocalyptic number.

It is an amenable number.

1666212061 is a deficient number, since it is larger than the sum of its proper divisors (484611).

1666212061 is an equidigital number, since it uses as much as digits as its factorization.

1666212061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484610.

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 1666212061 is about 40819.2609070767. The cubic root of 1666212061 is about 1185.5232927705.

The spelling of 1666212061 in words is "one billion, six hundred sixty-six million, two hundred twelve thousand, sixty-one".