861003977409 has 81 divisors (see below), whose sum is σ = 1336795180227. Its totient is φ = 533937655872.

The previous prime is 861003977401. The next prime is 861003977417. The reversal of 861003977409 is 904779300168.

It is a happy number.

The square root of 861003977409 is 927903.

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

861003977409 is a `hidden beast` number, since 86 + 100 + 397 + 74 + 0 + 9 = 666.

It is an interprime number because it is at equal distance from previous prime (861003977401) and next prime (861003977417).

It can be written as a sum of positive squares in only one way, i.e., 488747801025 + 372256176384 = 699105^2 + 610128^2 .

It is not a de Polignac number, because 861003977409 - 2³ = 861003977401 is a prime.

It is a super-2 number, since 2×861003977409² (a number of 25 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (861003977401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 3861004272 + ... + 3861004494.

Almost surely, 2^861003977409 is an apocalyptic number.

861003977409 is the 927903-rd square number.

861003977409 is the 463952-nd centered octagonal number.

It is an amenable number.

861003977409 is a deficient number, since it is larger than the sum of its proper divisors (475791202818).

861003977409 is an equidigital number, since it uses as much as digits as its factorization.

861003977409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 636 (or 318 counting only the distinct ones).

The product of its (nonzero) digits is 2286144, while the sum is 54.

The spelling of 861003977409 in words is "eight hundred sixty-one billion, three million, nine hundred seventy-seven thousand, four hundred nine".