2152721 has 4 divisors (see below), whose sum is σ = 2175012. Its totient is φ = 2130432.

The previous prime is 2152691. The next prime is 2152729. The reversal of 2152721 is 1272512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1597696 + 555025 = 1264^2 + 745^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2152721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2152693 and 2152702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2152729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11000 + ... + 11193.

It is an arithmetic number, because the mean of its divisors is an integer number (543753).

2^2152721 is an apocalyptic number.

It is an amenable number.

2152721 is a deficient number, since it is larger than the sum of its proper divisors (22291).

2152721 is an equidigital number, since it uses as much as digits as its factorization.

2152721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22290.

The product of its digits is 280, while the sum is 20.

The square root of 2152721 is about 1467.2153897775. The cubic root of 2152721 is about 129.1207130784.

The spelling of 2152721 in words is "two million, one hundred fifty-two thousand, seven hundred twenty-one".