87781853921 has 2 divisors, whose sum is σ = 87781853922. Its totient is φ = 87781853920.

The previous prime is 87781853897. The next prime is 87781853923. The reversal of 87781853921 is 12935818778.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72420730321 + 15361123600 = 269111^2 + 123940^2 .

It is a cyclic number.

It is not a de Polignac number, because 87781853921 - 2³⁴ = 70601984737 is a prime.

It is a Sophie Germain prime.

Together with 87781853923, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (87781853923) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43890926960 + 43890926961.

It is an arithmetic number, because the mean of its divisors is an integer number (43890926961).

Almost surely, 2^87781853921 is an apocalyptic number.

It is an amenable number.

87781853921 is a deficient number, since it is larger than the sum of its proper divisors (1).

87781853921 is an equidigital number, since it uses as much as digits as its factorization.

87781853921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6773760, while the sum is 59.

The spelling of 87781853921 in words is "eighty-seven billion, seven hundred eighty-one million, eight hundred fifty-three thousand, nine hundred twenty-one".