161680640 has 72 divisors (see below), whose sum is σ = 422519328. Its totient is φ = 58787840.

The previous prime is 161680613. The next prime is 161680643. The reversal of 161680640 is 46086161.

It is a happy number.

It is a super-2 number, since 2×161680640² = 52281258701619200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a junction number, because it is equal to n+sod(n) for n = 161680597 and 161680606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161680643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8339 + ... + 19821.

It is an arithmetic number, because the mean of its divisors is an integer number (5868324).

Almost surely, 2^161680640 is an apocalyptic number.

161680640 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 161680640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (211259664).

161680640 is an abundant number, since it is smaller than the sum of its proper divisors (260838688).

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

161680640 is a wasteful number, since it uses less digits than its factorization.

161680640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11515 (or 11501 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 161680640 is about 12715.3702266194. The cubic root of 161680640 is about 544.7777226723. Note that the first 4 decimals are identical.

The spelling of 161680640 in words is "one hundred sixty-one million, six hundred eighty thousand, six hundred forty".