2157840 has 140 divisors (see below), whose sum is σ = 7725324. Its totient is φ = 559872.

The previous prime is 2157839. The next prime is 2157851. The reversal of 2157840 is 487512.

It can be written as a sum of positive squares in 2 ways, for example, as 1411344 + 746496 = 1188^2 + 864^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 58302 + ... + 58338.

2^2157840 is an apocalyptic number.

2157840 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 2157840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3862662).

2157840 is an abundant number, since it is smaller than the sum of its proper divisors (5567484).

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

2157840 is an equidigital number, since it uses as much as digits as its factorization.

2157840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 2157840 is about 1468.9588149434. The cubic root of 2157840 is about 129.2229783372. Note that the first 3 decimals are identical.

The spelling of 2157840 in words is "two million, one hundred fifty-seven thousand, eight hundred forty".