1721257 has 2 divisors, whose sum is σ = 1721258. Its totient is φ = 1721256.

The previous prime is 1721243. The next prime is 1721261. The reversal of 1721257 is 7521271.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1687401 + 33856 = 1299^2 + 184^2 .

It is an emirp because it is prime and its reverse (7521271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1721257 - 2¹¹ = 1719209 is a prime.

It is not a weakly prime, because it can be changed into another prime (1721227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860628 + 860629.

It is an arithmetic number, because the mean of its divisors is an integer number (860629).

2^1721257 is an apocalyptic number.

It is an amenable number.

1721257 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721257 is an equidigital number, since it uses as much as digits as its factorization.

1721257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 980, while the sum is 25.

The square root of 1721257 is about 1311.9668440932. The cubic root of 1721257 is about 119.8437085670.

The spelling of 1721257 in words is "one million, seven hundred twenty-one thousand, two hundred fifty-seven".