161491500 has 144 divisors (see below), whose sum is σ = 539675136. Its totient is φ = 40512000.

The previous prime is 161491489. The next prime is 161491501. The reversal of 161491500 is 5194161.

161491500 is a `hidden beast` number, since 16 + 149 + 1 + 500 = 666.

It is not an unprimeable number, because it can be changed into a prime (161491501) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 75445 + ... + 77555.

It is an arithmetic number, because the mean of its divisors is an integer number (3747744).

Almost surely, 2^161491500 is an apocalyptic number.

161491500 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 161491500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (269837568).

161491500 is an abundant number, since it is smaller than the sum of its proper divisors (378183636).

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

161491500 is a wasteful number, since it uses less digits than its factorization.

161491500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2153 (or 2138 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 161491500 is about 12707.9305947113. The cubic root of 161491500 is about 544.5652060628.

The spelling of 161491500 in words is "one hundred sixty-one million, four hundred ninety-one thousand, five hundred".