1865918211861 has 16 divisors (see below), whose sum is σ = 2714114525760. Its totient is φ = 1130837992320.

The previous prime is 1865918211851. The next prime is 1865918211881. The reversal of 1865918211861 is 1681128195681.

It is a happy number.

It is not a de Polignac number, because 1865918211861 - 2²¹ = 1865916114709 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1865918211851) 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, 1316745 + ... + 2337873.

It is an arithmetic number, because the mean of its divisors is an integer number (169632157860).

Almost surely, 2^{1865918211861} is an apocalyptic number.

1865918211861 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1865918211861 is a deficient number, since it is larger than the sum of its proper divisors (848196313899).

1865918211861 is a wasteful number, since it uses less digits than its factorization.

1865918211861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1076516.

The product of its digits is 1658880, while the sum is 57.

The spelling of 1865918211861 in words is "one trillion, eight hundred sixty-five billion, nine hundred eighteen million, two hundred eleven thousand, eight hundred sixty-one".