1728307421 has 2 divisors, whose sum is σ = 1728307422. Its totient is φ = 1728307420.

The previous prime is 1728307417. The next prime is 1728307433. The reversal of 1728307421 is 1247038271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 921122500 + 807184921 = 30350^2 + 28411^2 .

It is a cyclic number.

It is not a de Polignac number, because 1728307421 - 2² = 1728307417 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1728300421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 864153710 + 864153711.

It is an arithmetic number, because the mean of its divisors is an integer number (864153711).

Almost surely, 2^1728307421 is an apocalyptic number.

It is an amenable number.

1728307421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1728307421 is an equidigital number, since it uses as much as digits as its factorization.

1728307421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18816, while the sum is 35.

The square root of 1728307421 is about 41572.9169171469. The cubic root of 1728307421 is about 1200.0711580489.

The spelling of 1728307421 in words is "one billion, seven hundred twenty-eight million, three hundred seven thousand, four hundred twenty-one".