2640402 has 18 divisors (see below), whose sum is σ = 5735847. Its totient is φ = 877836.

The previous prime is 2640397. The next prime is 2640409. The reversal of 2640402 is 2040462.

2640402 is a `hidden beast` number, since 264 + 0 + 402 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1320201 + 1320201 = 1149^2 + 1149^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=1149.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (2640409) 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 8 ways as a sum of consecutive naturals, for example, 6703 + ... + 7085.

2^2640402 is an apocalyptic number.

2640402 is an abundant number, since it is smaller than the sum of its proper divisors (3095445).

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

2640402 is an equidigital number, since it uses as much as digits as its factorization.

2640402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 2640402 is about 1624.9313831667. The cubic root of 2640402 is about 138.2154793708.

Multiplying 2640402 by its sum of digits (18), we get a square (47527236 = 6894²).

2640402 divided by its sum of digits (18) gives a square (146689 = 383²).

Adding to 2640402 its reverse (2040462), we get a palindrome (4680864).

The spelling of 2640402 in words is "two million, six hundred forty thousand, four hundred two".