4002640 has 20 divisors (see below), whose sum is σ = 9306324. Its totient is φ = 1601024.

The previous prime is 4002631. The next prime is 4002641. The reversal of 4002640 is 462004.

It can be written as a sum of positive squares in 2 ways, for example, as 646416 + 3356224 = 804^2 + 1832^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×4002640² = 32042253939200, which contains 22 as substring.

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

4002640 is a modest number, since divided by 2640 gives 400 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4002641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24937 + ... + 25096.

Almost surely, 2^4002640 is an apocalyptic number.

4002640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

4002640 is an abundant number, since it is smaller than the sum of its proper divisors (5303684).

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

4002640 is a wasteful number, since it uses less digits than its factorization.

4002640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50046 (or 50040 counting only the distinct ones).

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

The square root of 4002640 is about 2000.6598911359. The cubic root of 4002640 is about 158.7750203398.

Adding to 4002640 its reverse (462004), we get a palindrome (4464644).

The spelling of 4002640 in words is "four million, two thousand, six hundred forty".