165681720 has 64 divisors (see below), whose sum is σ = 552276000. Its totient is φ = 44181504.

The previous prime is 165681683. The next prime is 165681757. The reversal of 165681720 is 27186561.

It is an interprime number because it is at equal distance from previous prime (165681683) and next prime (165681757).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 75625 + ... + 77784.

Almost surely, 2^165681720 is an apocalyptic number.

165681720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

165681720 is an abundant number, since it is smaller than the sum of its proper divisors (386594280).

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

165681720 is a wasteful number, since it uses less digits than its factorization.

165681720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153429 (or 153419 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 165681720 is about 12871.7411409646. The cubic root of 165681720 is about 549.2349915207.

The spelling of 165681720 in words is "one hundred sixty-five million, six hundred eighty-one thousand, seven hundred twenty".