172211681 has 4 divisors (see below), whose sum is σ = 175461012. Its totient is φ = 168962352.

The previous prime is 172211651. The next prime is 172211729. The reversal of 172211681 is 186112271.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 186112271 = 601 ⋅309671.

It can be written as a sum of positive squares in 2 ways, for example, as 73805281 + 98406400 = 8591^2 + 9920^2 .

It is a cyclic number.

It is not a de Polignac number, because 172211681 - 2⁶ = 172211617 is a prime.

It is a super-2 number, since 2×172211681² = 59313726145691522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (172211651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1624586 + ... + 1624691.

It is an arithmetic number, because the mean of its divisors is an integer number (43865253).

Almost surely, 2^172211681 is an apocalyptic number.

It is an amenable number.

172211681 is a deficient number, since it is larger than the sum of its proper divisors (3249331).

172211681 is an equidigital number, since it uses as much as digits as its factorization.

172211681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3249330.

The product of its digits is 1344, while the sum is 29.

The square root of 172211681 is about 13122.9448295724. The cubic root of 172211681 is about 556.3578267424.

The spelling of 172211681 in words is "one hundred seventy-two million, two hundred eleven thousand, six hundred eighty-one".