199120021 has 2 divisors, whose sum is σ = 199120022. Its totient is φ = 199120020.

The previous prime is 199120013. The next prime is 199120081. The reversal of 199120021 is 120021991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 173211921 + 25908100 = 13161^2 + 5090^2 .

It is a cyclic number.

It is not a de Polignac number, because 199120021 - 2³ = 199120013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199120081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99560010 + 99560011.

It is an arithmetic number, because the mean of its divisors is an integer number (99560011).

Almost surely, 2^199120021 is an apocalyptic number.

It is an amenable number.

199120021 is a deficient number, since it is larger than the sum of its proper divisors (1).

199120021 is an equidigital number, since it uses as much as digits as its factorization.

199120021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 25.

The square root of 199120021 is about 14110.9893699910. The cubic root of 199120021 is about 583.9445952396.

The spelling of 199120021 in words is "one hundred ninety-nine million, one hundred twenty thousand, twenty-one".