161231728 has 40 divisors (see below), whose sum is σ = 358370912. Its totient is φ = 68836608.

The previous prime is 161231683. The next prime is 161231729. The reversal of 161231728 is 827132161.

It is a super-2 number, since 2×161231728² = 51991340227731968, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161231728.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161231729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28426 + ... + 33622.

Almost surely, 2^161231728 is an apocalyptic number.

It is an amenable number.

161231728 is an abundant number, since it is smaller than the sum of its proper divisors (197139184).

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

161231728 is a wasteful number, since it uses less digits than its factorization.

161231728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5489 (or 5483 counting only the distinct ones).

The product of its digits is 4032, while the sum is 31.

The square root of 161231728 is about 12697.7056195204. The cubic root of 161231728 is about 544.2730571220.

Adding to 161231728 its reverse (827132161), we get a palindrome (988363889).

The spelling of 161231728 in words is "one hundred sixty-one million, two hundred thirty-one thousand, seven hundred twenty-eight".