100781861 has 2 divisors, whose sum is σ = 100781862. Its totient is φ = 100781860.

The previous prime is 100781843. The next prime is 100781881. The reversal of 100781861 is 168187001.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 100300225 + 481636 = 10015^2 + 694^2 .

It is a cyclic number.

It is not a de Polignac number, because 100781861 - 2¹⁰ = 100780837 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (100781881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50390930 + 50390931.

It is an arithmetic number, because the mean of its divisors is an integer number (50390931).

Almost surely, 2^100781861 is an apocalyptic number.

It is an amenable number.

100781861 is a deficient number, since it is larger than the sum of its proper divisors (1).

100781861 is an equidigital number, since it uses as much as digits as its factorization.

100781861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 32.

The square root of 100781861 is about 10039.0169339433. The cubic root of 100781861 is about 465.3654367092.

The spelling of 100781861 in words is "one hundred million, seven hundred eighty-one thousand, eight hundred sixty-one".