91878174121 has 2 divisors, whose sum is σ = 91878174122. Its totient is φ = 91878174120.

The previous prime is 91878174067. The next prime is 91878174133. The reversal of 91878174121 is 12147187819.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 90637725721 + 1240448400 = 301061^2 + 35220^2 .

It is a cyclic number.

It is not a de Polignac number, because 91878174121 - 2³¹ = 89730690473 is a prime.

It is not a weakly prime, because it can be changed into another prime (91878174191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45939087060 + 45939087061.

It is an arithmetic number, because the mean of its divisors is an integer number (45939087061).

Almost surely, 2^91878174121 is an apocalyptic number.

It is an amenable number.

91878174121 is a deficient number, since it is larger than the sum of its proper divisors (1).

91878174121 is an equidigital number, since it uses as much as digits as its factorization.

91878174121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 225792, while the sum is 49.

The spelling of 91878174121 in words is "ninety-one billion, eight hundred seventy-eight million, one hundred seventy-four thousand, one hundred twenty-one".