861011649 has 9 divisors (see below), whose sum is σ = 1243810659. Its totient is φ = 573949080.

The previous prime is 861011623. The next prime is 861011651. The reversal of 861011649 is 946110168.

It is a happy number.

The square root of 861011649 is 29343.

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

861011649 is a `hidden beast` number, since 8 + 6 + 1 + 0 + 1 + 1 + 649 = 666.

It can be written as a sum of positive squares in only one way, i.e., 370832049 + 490179600 = 19257^2 + 22140^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 861011649 - 2¹³ = 861003457 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (861011609) 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 8 ways as a sum of consecutive naturals, for example, 83139 + ... + 92919.

Almost surely, 2^861011649 is an apocalyptic number.

861011649 is the 29343-rd square number.

861011649 is the 14672-nd centered octagonal number.

It is an amenable number.

861011649 is a deficient number, since it is larger than the sum of its proper divisors (382799010).

861011649 is an frugal number, since it uses more digits than its factorization.

861011649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19568 (or 9784 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The cubic root of 861011649 is about 951.3412813795.

Multiplying 861011649 by its sum of digits (36), we get a square (30996419364 = 176058²).

The spelling of 861011649 in words is "eight hundred sixty-one million, eleven thousand, six hundred forty-nine".