402581 has 2 divisors, whose sum is σ = 402582. Its totient is φ = 402580.

The previous prime is 402559. The next prime is 402583. The reversal of 402581 is 185204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 401956 + 625 = 634^2 + 25^2 .

It is a cyclic number.

It is not a de Polignac number, because 402581 - 2⁶ = 402517 is a prime.

It is a super-2 number, since 2×402581² = 324142923122, which contains 22 as substring.

Together with 402583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201290 + 201291.

It is an arithmetic number, because the mean of its divisors is an integer number (201291).

2⁴⁰²⁵⁸¹ is an apocalyptic number.

It is an amenable number.

402581 is a deficient number, since it is larger than the sum of its proper divisors (1).

402581 is an equidigital number, since it uses as much as digits as its factorization.

402581 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 402581 is about 634.4927107540. The cubic root of 402581 is about 73.8387650916.

Adding to 402581 its reverse (185204), we get a palindrome (587785).

The spelling of 402581 in words is "four hundred two thousand, five hundred eighty-one".