2405721 has 16 divisors (see below), whose sum is σ = 3478464. Its totient is φ = 1473024.

The previous prime is 2405707. The next prime is 2405729. The reversal of 2405721 is 1275042.

2405721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

2405721 is a nontrivial binomial coefficient, being equal to C(2194, 2).

It is not a de Polignac number, because 2405721 - 2⁹ = 2405209 is a prime.

It is not an unprimeable number, because it can be changed into a prime (2405729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1645 + ... + 2741.

It is an arithmetic number, because the mean of its divisors is an integer number (217404).

2^2405721 is an apocalyptic number.

2405721 is the 2193-rd triangular number and also the 1097-th hexagonal number.

It is an amenable number.

2405721 is a deficient number, since it is larger than the sum of its proper divisors (1072743).

2405721 is a wasteful number, since it uses less digits than its factorization.

2405721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1160.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 2405721 is about 1551.0386842371. The cubic root of 2405721 is about 133.9928896502.

The spelling of 2405721 in words is "two million, four hundred five thousand, seven hundred twenty-one".