402781 has 16 divisors (see below), whose sum is σ = 475200. Its totient is φ = 338688.

The previous prime is 402769. The next prime is 402797. The reversal of 402781 is 187204.

It is a 4-Lehmer number, since φ(402781) divides (402781-1)⁴.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-402781 is a prime.

It is a super-2 number, since 2×402781² = 324465067922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402751) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9346 + ... + 9388.

It is an arithmetic number, because the mean of its divisors is an integer number (29700).

2⁴⁰²⁷⁸¹ is an apocalyptic number.

It is an amenable number.

402781 is a deficient number, since it is larger than the sum of its proper divisors (72419).

402781 is a wasteful number, since it uses less digits than its factorization.

402781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 108.

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 402781 is about 634.6502974080. The cubic root of 402781 is about 73.8509906298.

Adding to 402781 its reverse (187204), we get a palindrome (589985).

The spelling of 402781 in words is "four hundred two thousand, seven hundred eighty-one".