1997557 has 2 divisors, whose sum is σ = 1997558. Its totient is φ = 1997556.

The previous prime is 1997543. The next prime is 1997587. The reversal of 1997557 is 7557991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1347921 + 649636 = 1161^2 + 806^2 .

It is a cyclic number.

It is not a de Polignac number, because 1997557 - 2¹⁵ = 1964789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1997507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 998778 + 998779.

It is an arithmetic number, because the mean of its divisors is an integer number (998779).

2^1997557 is an apocalyptic number.

It is an amenable number.

1997557 is a deficient number, since it is larger than the sum of its proper divisors (1).

1997557 is an equidigital number, since it uses as much as digits as its factorization.

1997557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 99225, while the sum is 43.

The square root of 1997557 is about 1413.3495675168. The cubic root of 1997557 is about 125.9407843023.

The spelling of 1997557 in words is "one million, nine hundred ninety-seven thousand, five hundred fifty-seven".