161999280 has 120 divisors (see below), whose sum is σ = 551884320. Its totient is φ = 42577920.

The previous prime is 161999269. The next prime is 161999291. The reversal of 161999280 is 82999161.

161999280 is a `hidden beast` number, since 1 + 619 + 9 + 9 + 28 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (161999269) and next prime (161999291).

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 49536 + ... + 52704.

It is an arithmetic number, because the mean of its divisors is an integer number (4599036).

Almost surely, 2^161999280 is an apocalyptic number.

161999280 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 161999280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (275942160).

161999280 is an abundant number, since it is smaller than the sum of its proper divisors (389885040).

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

161999280 is a wasteful number, since it uses less digits than its factorization.

161999280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3259 (or 3250 counting only the distinct ones).

The product of its (nonzero) digits is 69984, while the sum is 45.

The square root of 161999280 is about 12727.8937770552. The cubic root of 161999280 is about 545.1353702393.

The spelling of 161999280 in words is "one hundred sixty-one million, nine hundred ninety-nine thousand, two hundred eighty".