161991648 has 216 divisors, whose sum is σ = 577748808. Its totient is φ = 42674688.

The previous prime is 161991637. The next prime is 161991667. The reversal of 161991648 is 846199161.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 183015 + ... + 183897.

It is an arithmetic number, because the mean of its divisors is an integer number (2674763).

Almost surely, 2^161991648 is an apocalyptic number.

161991648 is a gapful number since it is divisible by the number (18) 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 161991648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (288874404).

161991648 is an abundant number, since it is smaller than the sum of its proper divisors (415757160).

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

161991648 is a wasteful number, since it uses less digits than its factorization.

161991648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 926 (or 908 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 161991648 is about 12727.5939595825. The cubic root of 161991648 is about 545.1268094225.

The spelling of 161991648 in words is "one hundred sixty-one million, nine hundred ninety-one thousand, six hundred forty-eight".