171720387 has 12 divisors (see below), whose sum is σ = 251535024. Its totient is φ = 112867440.

The previous prime is 171720359. The next prime is 171720389. The reversal of 171720387 is 783027171.

It is a happy number.

It is not a de Polignac number, because 171720387 - 2¹⁴ = 171704003 is a prime.

It is a super-2 number, since 2×171720387² = 58975782622859538, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (171720389) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 133728 + ... + 135005.

It is an arithmetic number, because the mean of its divisors is an integer number (20961252).

Almost surely, 2^171720387 is an apocalyptic number.

171720387 is a deficient number, since it is larger than the sum of its proper divisors (79814637).

171720387 is a wasteful number, since it uses less digits than its factorization.

171720387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268810 (or 268807 counting only the distinct ones).

The product of its (nonzero) digits is 16464, while the sum is 36.

The square root of 171720387 is about 13104.2125669572. The cubic root of 171720387 is about 555.8282544520.

The spelling of 171720387 in words is "one hundred seventy-one million, seven hundred twenty thousand, three hundred eighty-seven".