861561249 has 12 divisors (see below), whose sum is σ = 1177456848. Its totient is φ = 560361760.

The previous prime is 861561229. The next prime is 861561271. The reversal of 861561249 is 942165168.

It is not a de Polignac number, because 861561249 - 2⁷ = 861561121 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 861561249.

It is not an unprimeable number, because it can be changed into a prime (861561229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 80379 + ... + 90464.

It is an arithmetic number, because the mean of its divisors is an integer number (98121404).

Almost surely, 2^861561249 is an apocalyptic number.

It is an amenable number.

861561249 is a deficient number, since it is larger than the sum of its proper divisors (315895599).

861561249 is a wasteful number, since it uses less digits than its factorization.

861561249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170928 (or 170887 counting only the distinct ones).

The product of its digits is 103680, while the sum is 42.

The square root of 861561249 is about 29352.3636015909. The cubic root of 861561249 is about 951.5436580289.

The spelling of 861561249 in words is "eight hundred sixty-one million, five hundred sixty-one thousand, two hundred forty-nine".