171999990 has 64 divisors (see below), whose sum is σ = 462067200. Its totient is φ = 45526752.

The previous prime is 171999983. The next prime is 171999991. The reversal of 171999990 is 99999171.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (171999991) 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 31 ways as a sum of consecutive naturals, for example, 35239 + ... + 39821.

It is an arithmetic number, because the mean of its divisors is an integer number (7219800).

Almost surely, 2^171999990 is an apocalyptic number.

171999990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 171999990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (231033600).

171999990 is an abundant number, since it is smaller than the sum of its proper divisors (290067210).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

171999990 is a wasteful number, since it uses less digits than its factorization.

171999990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4738 (or 4732 counting only the distinct ones).

The product of its (nonzero) digits is 413343, while the sum is 54.

The square root of 171999990 is about 13114.8766673576. The cubic root of 171999990 is about 556.1297658744.

The spelling of 171999990 in words is "one hundred seventy-one million, nine hundred ninety-nine thousand, nine hundred ninety".