172018621 has 2 divisors, whose sum is σ = 172018622. Its totient is φ = 172018620.

The previous prime is 172018603. The next prime is 172018697. The reversal of 172018621 is 126810271.

172018621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 149084100 + 22934521 = 12210^2 + 4789^2 .

It is a cyclic number.

It is not a de Polignac number, because 172018621 - 2¹⁷ = 171887549 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 172018621.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172018921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86009310 + 86009311.

It is an arithmetic number, because the mean of its divisors is an integer number (86009311).

Almost surely, 2^172018621 is an apocalyptic number.

It is an amenable number.

172018621 is a deficient number, since it is larger than the sum of its proper divisors (1).

172018621 is an equidigital number, since it uses as much as digits as its factorization.

172018621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 28.

The square root of 172018621 is about 13115.5869483603. The cubic root of 172018621 is about 556.1498450996.

Adding to 172018621 its reverse (126810271), we get a palindrome (298828892).

The spelling of 172018621 in words is "one hundred seventy-two million, eighteen thousand, six hundred twenty-one".