1997645 has 16 divisors (see below), whose sum is σ = 2623152. Its totient is φ = 1451520.

The previous prime is 1997617. The next prime is 1997647. The reversal of 1997645 is 5467991.

It can be written as a sum of positive squares in 8 ways, for example, as 619369 + 1378276 = 787^2 + 1174^2 .

It is not a de Polignac number, because 1997645 - 2¹⁶ = 1932109 is a prime.

It is a super-3 number, since 3×1997645³ = 23915319789267333375, which contains 333 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1997647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4535 + ... + 4955.

It is an arithmetic number, because the mean of its divisors is an integer number (163947).

2^1997645 is an apocalyptic number.

It is an amenable number.

1997645 is a deficient number, since it is larger than the sum of its proper divisors (625507).

1997645 is a wasteful number, since it uses less digits than its factorization.

1997645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 512.

The product of its digits is 68040, while the sum is 41.

The square root of 1997645 is about 1413.3806988918. The cubic root of 1997645 is about 125.9426336657.

The spelling of 1997645 in words is "one million, nine hundred ninety-seven thousand, six hundred forty-five".