2118701781 has 24 divisors (see below), whose sum is σ = 3503724224. Its totient is φ = 1208545920.

The previous prime is 2118701771. The next prime is 2118701797. The reversal of 2118701781 is 1871078112.

It is not a de Polignac number, because 2118701781 - 2¹⁴ = 2118685397 is a prime.

It is a super-2 number, since 2×2118701781² = 8977794473625143922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2118701701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6525 + ... + 65421.

Almost surely, 2^2118701781 is an apocalyptic number.

2118701781 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2118701781 is a deficient number, since it is larger than the sum of its proper divisors (1385022443).

2118701781 is a wasteful number, since it uses less digits than its factorization.

2118701781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59481 (or 59478 counting only the distinct ones).

The product of its (nonzero) digits is 6272, while the sum is 36.

The square root of 2118701781 is about 46029.3578165066. The cubic root of 2118701781 is about 1284.3693819635.

Adding to 2118701781 its reverse (1871078112), we get a palindrome (3989779893).

The spelling of 2118701781 in words is "two billion, one hundred eighteen million, seven hundred one thousand, seven hundred eighty-one".