172199981 has 2 divisors, whose sum is σ = 172199982. Its totient is φ = 172199980.

The previous prime is 172199977. The next prime is 172200019. The reversal of 172199981 is 189991271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 95374756 + 76825225 = 9766^2 + 8765^2 .

It is a cyclic number.

It is not a de Polignac number, because 172199981 - 2² = 172199977 is a prime.

It is a super-2 number, since 2×172199981² = 59305666912800722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172199971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86099990 + 86099991.

It is an arithmetic number, because the mean of its divisors is an integer number (86099991).

Almost surely, 2^172199981 is an apocalyptic number.

It is an amenable number.

172199981 is a deficient number, since it is larger than the sum of its proper divisors (1).

172199981 is an equidigital number, since it uses as much as digits as its factorization.

172199981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 47.

The square root of 172199981 is about 13122.4990379119. The cubic root of 172199981 is about 556.3452268731.

The spelling of 172199981 in words is "one hundred seventy-two million, one hundred ninety-nine thousand, nine hundred eighty-one".