2121720 has 32 divisors (see below), whose sum is σ = 6365520. Its totient is φ = 565760.

The previous prime is 2121683. The next prime is 2121737. The reversal of 2121720 is 271212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 2121720.

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, 8721 + ... + 8960.

2^2121720 is an apocalyptic number.

2121720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

2121720 is an abundant number, since it is smaller than the sum of its proper divisors (4243800).

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

2121720 is a wasteful number, since it uses less digits than its factorization.

2121720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17695 (or 17691 counting only the distinct ones).

The product of its (nonzero) digits is 56, while the sum is 15.

The square root of 2121720 is about 1456.6125085279. The cubic root of 2121720 is about 128.4978979908.

Adding to 2121720 its reverse (271212), we get a palindrome (2392932).

The spelling of 2121720 in words is "two million, one hundred twenty-one thousand, seven hundred twenty".