401581 has 4 divisors (see below), whose sum is σ = 409212. Its totient is φ = 393952.

The previous prime is 401567. The next prime is 401587. The reversal of 401581 is 185104.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 108900 + 292681 = 330^2 + 541^2 .

It is a cyclic number.

It is not a de Polignac number, because 401581 - 2⁹ = 401069 is a prime.

It is a super-2 number, since 2×401581² = 322534599122, which contains 22 as substring.

It is an Ulam 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 (401587) 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, 3736 + ... + 3841.

It is an arithmetic number, because the mean of its divisors is an integer number (102303).

2⁴⁰¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

401581 is a deficient number, since it is larger than the sum of its proper divisors (7631).

401581 is an equidigital number, since it uses as much as digits as its factorization.

401581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7630.

The product of its (nonzero) digits is 160, while the sum is 19.

The square root of 401581 is about 633.7041896658. The cubic root of 401581 is about 73.7775765876. Note that the first 3 decimals are identical.

Adding to 401581 its reverse (185104), we get a palindrome (586685).

It can be divided in two parts, 4015 and 81, that added together give a 12-th power (4096 = 2¹²).

The spelling of 401581 in words is "four hundred one thousand, five hundred eighty-one".