12015857861 has 6 divisors (see below), whose sum is σ = 13977630630. Its totient is φ = 10299306696.

The previous prime is 12015857807. The next prime is 12015857863. The reversal of 12015857861 is 16875851021.

It can be written as a sum of positive squares in only one way, i.e., 11595197761 + 420660100 = 107681^2 + 20510^2 .

It is not a de Polignac number, because 12015857861 - 2¹⁴ = 12015841477 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12015857863) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 122610746 + ... + 122610843.

It is an arithmetic number, because the mean of its divisors is an integer number (2329605105).

Almost surely, 2^12015857861 is an apocalyptic number.

It is an amenable number.

12015857861 is a deficient number, since it is larger than the sum of its proper divisors (1961772769).

12015857861 is an equidigital number, since it uses as much as digits as its factorization.

12015857861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245221603 (or 245221596 counting only the distinct ones).

The product of its (nonzero) digits is 134400, while the sum is 44.

The spelling of 12015857861 in words is "twelve billion, fifteen million, eight hundred fifty-seven thousand, eight hundred sixty-one".