402640 has 40 divisors (see below), whose sum is σ = 1071360. Its totient is φ = 137856.

The previous prime is 402631. The next prime is 402691. The reversal of 402640 is 46204.

402640 = 2² + 3² + ... + 106².

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a plaindrome in base 11.

It is a congruent number.

It is an unprimeable number.

402640 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 201 + ... + 919.

It is an arithmetic number, because the mean of its divisors is an integer number (26784).

2⁴⁰²⁶⁴⁰ is an apocalyptic number.

402640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 402640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (535680).

402640 is an abundant number, since it is smaller than the sum of its proper divisors (668720).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

402640 is a wasteful number, since it uses less digits than its factorization.

402640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 739 (or 733 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 402640 is about 634.5392028866. The cubic root of 402640 is about 73.8423720464.

Adding to 402640 its reverse (46204), we get a palindrome (448844).

The spelling of 402640 in words is "four hundred two thousand, six hundred forty".