97878999987781 has 2 divisors, whose sum is σ = 97878999987782. Its totient is φ = 97878999987780.

The previous prime is 97878999987779. The next prime is 97878999987941. The reversal of 97878999987781 is 18778999987879.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 94489869948100 + 3389130039681 = 9720590^2 + 1840959^2 .

It is a cyclic number.

It is not a de Polignac number, because 97878999987781 - 2¹ = 97878999987779 is a prime.

It is a super-2 number, since 2×97878999987781² (a number of 29 digits) contains 22 as substring.

Together with 97878999987779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (97878999987721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 48939499993890 + 48939499993891.

It is an arithmetic number, because the mean of its divisors is an integer number (48939499993891).

Almost surely, 2^{97878999987781} is an apocalyptic number.

It is an amenable number.

97878999987781 is a deficient number, since it is larger than the sum of its proper divisors (1).

97878999987781 is an equidigital number, since it uses as much as digits as its factorization.

97878999987781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 580717154304, while the sum is 106.

The spelling of 97878999987781 in words is "ninety-seven trillion, eight hundred seventy-eight billion, nine hundred ninety-nine million, nine hundred eighty-seven thousand, seven hundred eighty-one".