2640400 has 120 divisors (see below), whose sum is σ = 7749504. Its totient is φ = 844800.

The previous prime is 2640397. The next prime is 2640409. The reversal of 2640400 is 40462.

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

It is not an unprimeable number, because it can be changed into a prime (2640409) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 64380 + ... + 64420.

2^2640400 is an apocalyptic number.

2640400 is a gapful number since it is divisible by the number (20) 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 2640400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3874752).

2640400 is an abundant number, since it is smaller than the sum of its proper divisors (5109104).

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

2640400 is a wasteful number, since it uses less digits than its factorization.

2640400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89 (or 78 counting only the distinct ones).

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

The square root of 2640400 is about 1624.9307677560. The cubic root of 2640400 is about 138.2154444732.

2640400 divided by its sum of digits (16) gives a triangular number (165025 = T₅₇₄).

Adding to 2640400 its reverse (40462), we get a palindrome (2680862).

It can be divided in two parts, 2 and 640400, that multiplied together give a triangular number (1280800 = T₁₆₀₀).

The spelling of 2640400 in words is "two million, six hundred forty thousand, four hundred".