189728261 has 4 divisors (see below), whose sum is σ = 189756972. Its totient is φ = 189699552.

The previous prime is 189728257. The next prime is 189728291. The reversal of 189728261 is 162827981.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 162827981 = 151 ⋅1078331.

It can be written as a sum of positive squares in 2 ways, for example, as 130530625 + 59197636 = 11425^2 + 7694^2 .

It is a cyclic number.

It is not a de Polignac number, because 189728261 - 2² = 189728257 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (189728291) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1115 + ... + 19511.

It is an arithmetic number, because the mean of its divisors is an integer number (47439243).

Almost surely, 2^189728261 is an apocalyptic number.

It is an amenable number.

189728261 is a deficient number, since it is larger than the sum of its proper divisors (28711).

189728261 is a wasteful number, since it uses less digits than its factorization.

189728261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28710.

The product of its digits is 96768, while the sum is 44.

The square root of 189728261 is about 13774.1882156445. The cubic root of 189728261 is about 574.6155070364.

It can be divided in two parts, 18 and 9728261, that added together give a palindrome (9728279).

The spelling of 189728261 in words is "one hundred eighty-nine million, seven hundred twenty-eight thousand, two hundred sixty-one".