171772421 has 4 divisors (see below), whose sum is σ = 172005600. Its totient is φ = 171539244.

The previous prime is 171772387. The next prime is 171772429. The reversal of 171772421 is 124277171.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 171772421 - 2¹⁸ = 171510277 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171772429) 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 in 3 ways as a sum of consecutive naturals, for example, 115481 + ... + 116958.

It is an arithmetic number, because the mean of its divisors is an integer number (43001400).

Almost surely, 2^171772421 is an apocalyptic number.

It is an amenable number.

171772421 is a deficient number, since it is larger than the sum of its proper divisors (233179).

171772421 is an equidigital number, since it uses as much as digits as its factorization.

171772421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233178.

The product of its digits is 5488, while the sum is 32.

The square root of 171772421 is about 13106.1978086705. The cubic root of 171772421 is about 555.8843903738.

The spelling of 171772421 in words is "one hundred seventy-one million, seven hundred seventy-two thousand, four hundred twenty-one".