199975021 has 2 divisors, whose sum is σ = 199975022. Its totient is φ = 199975020.

The previous prime is 199975007. The next prime is 199975031. The reversal of 199975021 is 120579991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 193599396 + 6375625 = 13914^2 + 2525^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199975021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199975031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99987510 + 99987511.

It is an arithmetic number, because the mean of its divisors is an integer number (99987511).

Almost surely, 2^199975021 is an apocalyptic number.

It is an amenable number.

199975021 is a deficient number, since it is larger than the sum of its proper divisors (1).

199975021 is an equidigital number, since it uses as much as digits as its factorization.

199975021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51030, while the sum is 43.

The square root of 199975021 is about 14141.2524551399. The cubic root of 199975021 is about 584.7792002826.

The spelling of 199975021 in words is "one hundred ninety-nine million, nine hundred seventy-five thousand, twenty-one".