2156640 has 48 divisors (see below), whose sum is σ = 6794928. Its totient is φ = 574976.

The previous prime is 2156629. The next prime is 2156647. The reversal of 2156640 is 466512.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 2156640.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2156647) 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 7 ways as a sum of consecutive naturals, for example, 1767 + ... + 2726.

It is an arithmetic number, because the mean of its divisors is an integer number (141561).

2^2156640 is an apocalyptic number.

2156640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2156640 is an abundant number, since it is smaller than the sum of its proper divisors (4638288).

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

2156640 is a wasteful number, since it uses less digits than its factorization.

2156640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4511 (or 4503 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 2156640 is about 1468.5503055735. The cubic root of 2156640 is about 129.1990197602.

The spelling of 2156640 in words is "two million, one hundred fifty-six thousand, six hundred forty".