1861663609 has 9 divisors (see below), whose sum is σ = 2016491823. Its totient is φ = 1717940952.

The previous prime is 1861663603. The next prime is 1861663627. The reversal of 1861663609 is 9063661681.

The square root of 1861663609 is 43147.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 275394025 + 1586269584 = 16595^2 + 39828^2 .

It is not a de Polignac number, because 1861663609 - 2⁵ = 1861663577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1861663603) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 559252 + ... + 562570.

It is an arithmetic number, because the mean of its divisors is an integer number (224054647).

Almost surely, 2^1861663609 is an apocalyptic number.

1861663609 is the 43147-th square number.

1861663609 is the 21574-th centered octagonal number.

It is an amenable number.

1861663609 is a deficient number, since it is larger than the sum of its proper divisors (154828214).

1861663609 is an frugal number, since it uses more digits than its factorization.

1861663609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6664 (or 3332 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 46.

The cubic root of 1861663609 is about 1230.1754897559.

The spelling of 1861663609 in words is "one billion, eight hundred sixty-one million, six hundred sixty-three thousand, six hundred nine".