1017785861 has 4 divisors (see below), whose sum is σ = 1018303692. Its totient is φ = 1017268032.

The previous prime is 1017785837. The next prime is 1017785887. The reversal of 1017785861 is 1685877101.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1685877101 = 223 ⋅7559987.

It can be written as a sum of positive squares in 2 ways, for example, as 285812836 + 731973025 = 16906^2 + 27055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1017785861 - 2²⁶ = 950676997 is a prime.

It is a super-2 number, since 2×1017785861² = 2071776117703022642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1017785891) 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, 255956 + ... + 259901.

It is an arithmetic number, because the mean of its divisors is an integer number (254575923).

Almost surely, 2^1017785861 is an apocalyptic number.

It is an amenable number.

1017785861 is a deficient number, since it is larger than the sum of its proper divisors (517831).

1017785861 is an equidigital number, since it uses as much as digits as its factorization.

1017785861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 517830.

The product of its (nonzero) digits is 94080, while the sum is 44.

The square root of 1017785861 is about 31902.7563229261. The cubic root of 1017785861 is about 1005.8938150331.

The spelling of 1017785861 in words is "one billion, seventeen million, seven hundred eighty-five thousand, eight hundred sixty-one".