121998778901 has 2 divisors, whose sum is σ = 121998778902. Its totient is φ = 121998778900.

The previous prime is 121998778861. The next prime is 121998778919. The reversal of 121998778901 is 109877899121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 94987856401 + 27010922500 = 308201^2 + 164350^2 .

It is an emirp because it is prime and its reverse (109877899121) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-121998778901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121998778921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60999389450 + 60999389451.

It is an arithmetic number, because the mean of its divisors is an integer number (60999389451).

Almost surely, 2^121998778901 is an apocalyptic number.

It is an amenable number.

121998778901 is a deficient number, since it is larger than the sum of its proper divisors (1).

121998778901 is an equidigital number, since it uses as much as digits as its factorization.

121998778901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4572288, while the sum is 62.

The spelling of 121998778901 in words is "one hundred twenty-one billion, nine hundred ninety-eight million, seven hundred seventy-eight thousand, nine hundred one".