2161640 has 32 divisors (see below), whose sum is σ = 5239080. Its totient is φ = 797952.

The previous prime is 2161639. The next prime is 2161697. The reversal of 2161640 is 461612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1304164 + 857476 = 1142^2 + 926^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1559 + ... + 2598.

2^2161640 is an apocalyptic number.

2161640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2161640 is an abundant number, since it is smaller than the sum of its proper divisors (3077440).

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

2161640 is a wasteful number, since it uses less digits than its factorization.

2161640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4181 (or 4177 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 2161640 is about 1470.2516791352. The cubic root of 2161640 is about 129.2987886153.

The spelling of 2161640 in words is "two million, one hundred sixty-one thousand, six hundred forty".