155761 has 4 divisors (see below), whose sum is σ = 157300. Its totient is φ = 154224.

The previous prime is 155747. The next prime is 155773. The reversal of 155761 is 167551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 167551 = 137 ⋅1223.

It can be written as a sum of positive squares in 2 ways, for example, as 53361 + 102400 = 231^2 + 320^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155761 is a prime.

It is a super-2 number, since 2×155761² = 48522978242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 606 + ... + 823.

It is an arithmetic number, because the mean of its divisors is an integer number (39325).

2¹⁵⁵⁷⁶¹ is an apocalyptic number.

155761 is the 177-th centered decagonal number.

It is an amenable number.

155761 is a deficient number, since it is larger than the sum of its proper divisors (1539).

155761 is a wasteful number, since it uses less digits than its factorization.

155761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1538.

The product of its digits is 1050, while the sum is 25.

The square root of 155761 is about 394.6656813051. The cubic root of 155761 is about 53.8046208770.

It can be divided in two parts, 15 and 5761, that added together give a square (5776 = 76²).

The spelling of 155761 in words is "one hundred fifty-five thousand, seven hundred sixty-one".