402181 has 4 divisors (see below), whose sum is σ = 433132. Its totient is φ = 371232.

The previous prime is 402139. The next prime is 402197. The reversal of 402181 is 181204.

It is a happy number.

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 52900 + 349281 = 230^2 + 591^2 .

It is a cyclic number.

It is not a de Polignac number, because 402181 - 2⁷ = 402053 is a prime.

It is a super-2 number, since 2×402181² = 323499113522, which contains 22 as substring.

It is a Duffinian number.

402181 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402131) 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, 15456 + ... + 15481.

It is an arithmetic number, because the mean of its divisors is an integer number (108283).

2⁴⁰²¹⁸¹ is an apocalyptic number.

It is an amenable number.

402181 is a deficient number, since it is larger than the sum of its proper divisors (30951).

402181 is a wasteful number, since it uses less digits than its factorization.

402181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30950.

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 402181 is about 634.1774199702. The cubic root of 402181 is about 73.8143018627.

Adding to 402181 its reverse (181204), we get a palindrome (583385).

The spelling of 402181 in words is "four hundred two thousand, one hundred eighty-one".