151581 has 4 divisors (see below), whose sum is σ = 202112. Its totient is φ = 101052.

The previous prime is 151579. The next prime is 151597. The reversal of 151581 is 185151.

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: 185151 = 3 ⋅61717.

It is not a de Polignac number, because 151581 - 2¹ = 151579 is a prime.

It is a super-2 number, since 2×151581² = 45953599122, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (151531) 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, 25261 + ... + 25266.

It is an arithmetic number, because the mean of its divisors is an integer number (50528).

2¹⁵¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

151581 is a deficient number, since it is larger than the sum of its proper divisors (50531).

151581 is an equidigital number, since it uses as much as digits as its factorization.

151581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50530.

The product of its digits is 200, while the sum is 21.

The square root of 151581 is about 389.3340468030. The cubic root of 151581 is about 53.3189501145.

It can be divided in two parts, 1515 and 81, that added together give a triangular number (1596 = T₅₆).

The spelling of 151581 in words is "one hundred fifty-one thousand, five hundred eighty-one".