161217856 has 56 divisors (see below), whose sum is σ = 344692224. Its totient is φ = 74595840.

The previous prime is 161217827. The next prime is 161217911. The reversal of 161217856 is 658712161.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43866 + ... + 47398.

Almost surely, 2^161217856 is an apocalyptic number.

161217856 is a gapful number since it is divisible by the number (16) 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 161217856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172346112).

161217856 is an abundant number, since it is smaller than the sum of its proper divisors (183474368).

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

161217856 is a wasteful number, since it uses less digits than its factorization.

161217856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3599 (or 3589 counting only the distinct ones).

The product of its digits is 20160, while the sum is 37.

The square root of 161217856 is about 12697.1593673546. The cubic root of 161217856 is about 544.2574473483.

The spelling of 161217856 in words is "one hundred sixty-one million, two hundred seventeen thousand, eight hundred fifty-six".