2102061781 has 16 divisors (see below), whose sum is σ = 2315280240. Its totient is φ = 1899555840.

The previous prime is 2102061757. The next prime is 2102061799. The reversal of 2102061781 is 1871602012.

It can be written as a sum of positive squares in 8 ways, for example, as 574033681 + 1528028100 = 23959^2 + 39090^2 .

It is a cyclic number.

It is not a de Polignac number, because 2102061781 - 2⁵ = 2102061749 is a prime.

It is a super-2 number, since 2×2102061781² = 8837327462281783922, 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 (2102061881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 77455 + ... + 101011.

It is an arithmetic number, because the mean of its divisors is an integer number (144705015).

Almost surely, 2^2102061781 is an apocalyptic number.

It is an amenable number.

2102061781 is a deficient number, since it is larger than the sum of its proper divisors (213218459).

2102061781 is a wasteful number, since it uses less digits than its factorization.

2102061781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23784.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 2102061781 is about 45848.2473056495. The cubic root of 2102061781 is about 1280.9981189856.

Adding to 2102061781 its reverse (1871602012), we get a palindrome (3973663793).

The spelling of 2102061781 in words is "two billion, one hundred two million, sixty-one thousand, seven hundred eighty-one".