161783261 has 2 divisors, whose sum is σ = 161783262. Its totient is φ = 161783260.

The previous prime is 161783239. The next prime is 161783269. The reversal of 161783261 is 162387161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 157502500 + 4280761 = 12550^2 + 2069^2 .

It is an emirp because it is prime and its reverse (162387161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161783261 - 2⁶ = 161783197 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161783269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80891630 + 80891631.

It is an arithmetic number, because the mean of its divisors is an integer number (80891631).

Almost surely, 2^161783261 is an apocalyptic number.

It is an amenable number.

161783261 is a deficient number, since it is larger than the sum of its proper divisors (1).

161783261 is an equidigital number, since it uses as much as digits as its factorization.

161783261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12096, while the sum is 35.

The square root of 161783261 is about 12719.4048996012. The cubic root of 161783261 is about 544.8929576829.

The spelling of 161783261 in words is "one hundred sixty-one million, seven hundred eighty-three thousand, two hundred sixty-one".