161577720 has 192 divisors, whose sum is σ = 558252000. Its totient is φ = 41564160.

The previous prime is 161577709. The next prime is 161577721. The reversal of 161577720 is 27775161.

161577720 is a `hidden beast` number, since 1 + 61 + 577 + 7 + 20 = 666.

It is a super-2 number, since 2×161577720² = 52214719200796800, which contains 22 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161577721) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1815436 + ... + 1815524.

Almost surely, 2^161577720 is an apocalyptic number.

161577720 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 161577720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (279126000).

161577720 is an abundant number, since it is smaller than the sum of its proper divisors (396674280).

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

161577720 is a wasteful number, since it uses less digits than its factorization.

161577720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 191 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 20580, while the sum is 36.

The square root of 161577720 is about 12711.3225118396. The cubic root of 161577720 is about 544.6621029244.

The spelling of 161577720 in words is "one hundred sixty-one million, five hundred seventy-seven thousand, seven hundred twenty".