2116721 has 4 divisors (see below), whose sum is σ = 2241252. Its totient is φ = 1992192.

The previous prime is 2116717. The next prime is 2116729. The reversal of 2116721 is 1276112.

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 579121 + 1537600 = 761^2 + 1240^2 .

It is a cyclic number.

It is not a de Polignac number, because 2116721 - 2² = 2116717 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2116693 and 2116702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2116729) 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, 62240 + ... + 62273.

It is an arithmetic number, because the mean of its divisors is an integer number (560313).

2^2116721 is an apocalyptic number.

It is an amenable number.

2116721 is a deficient number, since it is larger than the sum of its proper divisors (124531).

2116721 is a wasteful number, since it uses less digits than its factorization.

2116721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124530.

The product of its digits is 168, while the sum is 20.

The square root of 2116721 is about 1454.8955288955. The cubic root of 2116721 is about 128.3969003499.

The spelling of 2116721 in words is "two million, one hundred sixteen thousand, seven hundred twenty-one".