1721356261 has 2 divisors, whose sum is σ = 1721356262. Its totient is φ = 1721356260.

The previous prime is 1721356229. The next prime is 1721356337. The reversal of 1721356261 is 1626531271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1035230625 + 686125636 = 32175^2 + 26194^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721356261 - 2⁵ = 1721356229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721350261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860678130 + 860678131.

It is an arithmetic number, because the mean of its divisors is an integer number (860678131).

Almost surely, 2^1721356261 is an apocalyptic number.

It is an amenable number.

1721356261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721356261 is an equidigital number, since it uses as much as digits as its factorization.

1721356261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 34.

The square root of 1721356261 is about 41489.2306629082. The cubic root of 1721356261 is about 1198.4601222794.

The spelling of 1721356261 in words is "one billion, seven hundred twenty-one million, three hundred fifty-six thousand, two hundred sixty-one".