199791120421 has 2 divisors, whose sum is σ = 199791120422. Its totient is φ = 199791120420.

The previous prime is 199791120371. The next prime is 199791120479. The reversal of 199791120421 is 124021197991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 124118813025 + 75672307396 = 352305^2 + 275086^2 .

It is a cyclic number.

It is not a de Polignac number, because 199791120421 - 2¹⁵ = 199791087653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199791120121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99895560210 + 99895560211.

It is an arithmetic number, because the mean of its divisors is an integer number (99895560211).

Almost surely, 2^199791120421 is an apocalyptic number.

It is an amenable number.

199791120421 is a deficient number, since it is larger than the sum of its proper divisors (1).

199791120421 is an equidigital number, since it uses as much as digits as its factorization.

199791120421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81648, while the sum is 46.

The spelling of 199791120421 in words is "one hundred ninety-nine billion, seven hundred ninety-one million, one hundred twenty thousand, four hundred twenty-one".