1800660061 has 2 divisors, whose sum is σ = 1800660062. Its totient is φ = 1800660060.

The previous prime is 1800660047. The next prime is 1800660089. The reversal of 1800660061 is 1600660081.

1800660061 = 30005² + 30006².

It is an a-pointer prime, because the next prime (1800660089) can be obtained adding 1800660061 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 900360036 + 900300025 = 30006^2 + 30005^2 .

It is an emirp because it is prime and its reverse (1600660081) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1800660061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1800660031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 900330030 + 900330031.

It is an arithmetic number, because the mean of its divisors is an integer number (900330031).

Almost surely, 2^1800660061 is an apocalyptic number.

1800660061 is the 30006-th centered square number.

It is an amenable number.

1800660061 is a deficient number, since it is larger than the sum of its proper divisors (1).

1800660061 is an equidigital number, since it uses as much as digits as its factorization.

1800660061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 1800660061 is about 42434.1850516774. The cubic root of 1800660061 is about 1216.5890707336.

The spelling of 1800660061 in words is "one billion, eight hundred million, six hundred sixty thousand, sixty-one".