5655721 has 2 divisors, whose sum is σ = 5655722. Its totient is φ = 5655720.

The previous prime is 5655659. The next prime is 5655731. The reversal of 5655721 is 1275565.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3111696 + 2544025 = 1764^2 + 1595^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-5655721 is a prime.

It is an Ulam number.

5655721 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (5655731) 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 as a sum of consecutive naturals, namely, 2827860 + 2827861.

It is an arithmetic number, because the mean of its divisors is an integer number (2827861).

Almost surely, 2^5655721 is an apocalyptic number.

It is an amenable number.

5655721 is a deficient number, since it is larger than the sum of its proper divisors (1).

5655721 is an equidigital number, since it uses as much as digits as its factorization.

5655721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10500, while the sum is 31.

The square root of 5655721 is about 2378.1759817137. The cubic root of 5655721 is about 178.1678444594.

The spelling of 5655721 in words is "five million, six hundred fifty-five thousand, seven hundred twenty-one".