1866016021 has 2 divisors, whose sum is σ = 1866016022. Its totient is φ = 1866016020.

The previous prime is 1866015979. The next prime is 1866016027. The reversal of 1866016021 is 1206106681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1607127921 + 258888100 = 40089^2 + 16090^2 .

It is a cyclic number.

It is not a de Polignac number, because 1866016021 - 2²¹ = 1863918869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1866016027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 933008010 + 933008011.

It is an arithmetic number, because the mean of its divisors is an integer number (933008011).

Almost surely, 2^1866016021 is an apocalyptic number.

It is an amenable number.

1866016021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1866016021 is an equidigital number, since it uses as much as digits as its factorization.

1866016021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 1866016021 is about 43197.4075726773. The cubic root of 1866016021 is about 1231.1334256883.

The spelling of 1866016021 in words is "one billion, eight hundred sixty-six million, sixteen thousand, twenty-one".