172499981 has 2 divisors, whose sum is σ = 172499982. Its totient is φ = 172499980.

The previous prime is 172499953. The next prime is 172499983. The reversal of 172499981 is 189994271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 124322500 + 48177481 = 11150^2 + 6941^2 .

It is an emirp because it is prime and its reverse (189994271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 172499981 - 2¹⁰ = 172498957 is a prime.

It is a super-2 number, since 2×172499981² = 59512486890000722, which contains 22 as substring.

Together with 172499983, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172499983) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86249990 + 86249991.

It is an arithmetic number, because the mean of its divisors is an integer number (86249991).

Almost surely, 2^172499981 is an apocalyptic number.

It is an amenable number.

172499981 is a deficient number, since it is larger than the sum of its proper divisors (1).

172499981 is an equidigital number, since it uses as much as digits as its factorization.

172499981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 326592, while the sum is 50.

The square root of 172499981 is about 13133.9248132460. The cubic root of 172499981 is about 556.6681203224.

The spelling of 172499981 in words is "one hundred seventy-two million, four hundred ninety-nine thousand, nine hundred eighty-one".