161261 has 4 divisors (see below), whose sum is σ = 162624. Its totient is φ = 159900.

The previous prime is 161237. The next prime is 161263. The reversal of 161261 is 162161.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 162161 = 31 ⋅5231.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161261 is a prime.

It is a super-2 number, since 2×161261² = 52010220242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161263) 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, 485 + ... + 746.

It is an arithmetic number, because the mean of its divisors is an integer number (40656).

2¹⁶¹²⁶¹ is an apocalyptic number.

It is an amenable number.

161261 is a deficient number, since it is larger than the sum of its proper divisors (1363).

161261 is a wasteful number, since it uses less digits than its factorization.

161261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1362.

The product of its digits is 72, while the sum is 17.

The square root of 161261 is about 401.5731564734. The cubic root of 161261 is about 54.4305993147.

Subtracting 161261 from its reverse (162161), we obtain a square (900 = 30²).

The spelling of 161261 in words is "one hundred sixty-one thousand, two hundred sixty-one".