861131815 has 16 divisors (see below), whose sum is σ = 1075931136. Its totient is φ = 661075200.

The previous prime is 861131797. The next prime is 861131819. The reversal of 861131815 is 518131168.

It is not a de Polignac number, because 861131815 - 2¹¹ = 861129767 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (861131819) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21927 + ... + 46936.

It is an arithmetic number, because the mean of its divisors is an integer number (67245696).

Almost surely, 2^861131815 is an apocalyptic number.

861131815 is a deficient number, since it is larger than the sum of its proper divisors (214799321).

861131815 is a wasteful number, since it uses less digits than its factorization.

861131815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68970.

The product of its digits is 5760, while the sum is 34.

The square root of 861131815 is about 29345.0475378726. The cubic root of 861131815 is about 951.3855369010.

The spelling of 861131815 in words is "eight hundred sixty-one million, one hundred thirty-one thousand, eight hundred fifteen".