402661 has 16 divisors (see below), whose sum is σ = 499968. Its totient is φ = 316800.

The previous prime is 402631. The next prime is 402691. The reversal of 402661 is 166204.

It is an interprime number because it is at equal distance from previous prime (402631) and next prime (402691).

It is a cyclic number.

It is not a de Polignac number, because 402661 - 2¹⁵ = 369893 is a prime.

It is a plaindrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402601) 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, 6571 + ... + 6631.

It is an arithmetic number, because the mean of its divisors is an integer number (31248).

2⁴⁰²⁶⁶¹ is an apocalyptic number.

402661 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

402661 is a deficient number, since it is larger than the sum of its proper divisors (97307).

402661 is a wasteful number, since it uses less digits than its factorization.

402661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 402661 is about 634.5557501118. Note that the first 3 decimals coincide. The cubic root of 402661 is about 73.8436557927.

Adding to 402661 its reverse (166204), we get a palindrome (568865).

It can be divided in two parts, 40 and 2661, that added together give a triangular number (2701 = T₇₃).

The spelling of 402661 in words is "four hundred two thousand, six hundred sixty-one".