2001810781 has 2 divisors, whose sum is σ = 2001810782. Its totient is φ = 2001810780.

The previous prime is 2001810763. The next prime is 2001810787. The reversal of 2001810781 is 1870181002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1908379225 + 93431556 = 43685^2 + 9666^2 .

It is a cyclic number.

It is not a de Polignac number, because 2001810781 - 2⁷ = 2001810653 is a prime.

It is a super-2 number, since 2×2001810781² = 8014492805855659922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2001810787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1000905390 + 1000905391.

It is an arithmetic number, because the mean of its divisors is an integer number (1000905391).

Almost surely, 2^2001810781 is an apocalyptic number.

It is an amenable number.

2001810781 is a deficient number, since it is larger than the sum of its proper divisors (1).

2001810781 is an equidigital number, since it uses as much as digits as its factorization.

2001810781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 896, while the sum is 28.

The square root of 2001810781 is about 44741.6001166699. The cubic root of 2001810781 is about 1260.3011753804.

Adding to 2001810781 its reverse (1870181002), we get a palindrome (3871991783).

The spelling of 2001810781 in words is "two billion, one million, eight hundred ten thousand, seven hundred eighty-one".