2656721 has 2 divisors, whose sum is σ = 2656722. Its totient is φ = 2656720.

The previous prime is 2656699. The next prime is 2656727. The reversal of 2656721 is 1276562.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2560000 + 96721 = 1600^2 + 311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2656721 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (2656727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1328360 + 1328361.

It is an arithmetic number, because the mean of its divisors is an integer number (1328361).

2^2656721 is an apocalyptic number.

It is an amenable number.

2656721 is a deficient number, since it is larger than the sum of its proper divisors (1).

2656721 is an equidigital number, since it uses as much as digits as its factorization.

2656721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 29.

The square root of 2656721 is about 1629.9450910997. The cubic root of 2656721 is about 138.4996415948.

The spelling of 2656721 in words is "two million, six hundred fifty-six thousand, seven hundred twenty-one".