861663309 has 32 divisors (see below), whose sum is σ = 1312464384. Its totient is φ = 498140160.

The previous prime is 861663263. The next prime is 861663323. The reversal of 861663309 is 903366168.

It is not a de Polignac number, because 861663309 - 2⁷ = 861663181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861663359) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 543532 + ... + 545114.

It is an arithmetic number, because the mean of its divisors is an integer number (41014512).

Almost surely, 2^861663309 is an apocalyptic number.

It is an amenable number.

861663309 is a deficient number, since it is larger than the sum of its proper divisors (450801075).

861663309 is a wasteful number, since it uses less digits than its factorization.

861663309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2437.

The product of its (nonzero) digits is 139968, while the sum is 42.

The square root of 861663309 is about 29354.1020813105. The cubic root of 861663309 is about 951.5812296318.

The spelling of 861663309 in words is "eight hundred sixty-one million, six hundred sixty-three thousand, three hundred nine".