2002020781 has 4 divisors (see below), whose sum is σ = 2039794812. Its totient is φ = 1964246752.

The previous prime is 2002020751. The next prime is 2002020799. The reversal of 2002020781 is 1870202002.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1870202002 = 2 ⋅935101001.

It can be written as a sum of positive squares in 2 ways, for example, as 943104100 + 1058916681 = 30710^2 + 32541^2 .

It is a cyclic number.

It is not a de Polignac number, because 2002020781 - 2⁷ = 2002020653 is a prime.

It is a super-2 number, since 2×2002020781² = 8016174415111699922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2002020721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18886936 + ... + 18887041.

It is an arithmetic number, because the mean of its divisors is an integer number (509948703).

Almost surely, 2^2002020781 is an apocalyptic number.

It is an amenable number.

2002020781 is a deficient number, since it is larger than the sum of its proper divisors (37774031).

2002020781 is an equidigital number, since it uses as much as digits as its factorization.

2002020781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37774030.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 2002020781 is about 44743.9468643525. The cubic root of 2002020781 is about 1260.3452444794.

Adding to 2002020781 its reverse (1870202002), we get a palindrome (3872222783).

The spelling of 2002020781 in words is "two billion, two million, twenty thousand, seven hundred eighty-one".