87781781 has 2 divisors, whose sum is σ = 87781782. Its totient is φ = 87781780.

The previous prime is 87781763. The next prime is 87781819. The reversal of 87781781 is 18718778.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 85192900 + 2588881 = 9230^2 + 1609^2 .

It is a cyclic number.

It is not a de Polignac number, because 87781781 - 2¹⁰ = 87780757 is a prime.

It is a super-2 number, since 2×87781781² = 15411282151063922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (87711781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43890890 + 43890891.

It is an arithmetic number, because the mean of its divisors is an integer number (43890891).

Almost surely, 2^87781781 is an apocalyptic number.

It is an amenable number.

87781781 is a deficient number, since it is larger than the sum of its proper divisors (1).

87781781 is an equidigital number, since it uses as much as digits as its factorization.

87781781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 175616, while the sum is 47.

The square root of 87781781 is about 9369.1931883167. The cubic root of 87781781 is about 444.4280511291.

The spelling of 87781781 in words is "eighty-seven million, seven hundred eighty-one thousand, seven hundred eighty-one".