1997800605 has 30 divisors (see below), whose sum is σ = 3582855738. Its totient is φ = 1065013920.

The previous prime is 1997800579. The next prime is 1997800639. The reversal of 1997800605 is 5060087991.

It can be written as a sum of positive squares in 3 ways, for example, as 465782724 + 1532017881 = 21582^2 + 39141^2 .

It is not a de Polignac number, because 1997800605 - 2⁹ = 1997800093 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 898395 + ... + 900615.

Almost surely, 2^1997800605 is an apocalyptic number.

1997800605 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1997800605 is a deficient number, since it is larger than the sum of its proper divisors (1585055133).

1997800605 is an frugal number, since it uses more digits than its factorization.

1997800605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4459 (or 2229 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 1997800605 is about 44696.7628022433. The cubic root of 1997800605 is about 1259.4590364855.

Multiplying 1997800605 by its sum of digits (45), we get a square (89901027225 = 299835²).

1997800605 divided by its sum of digits (45) gives a square (44395569 = 6663²).

The spelling of 1997800605 in words is "one billion, nine hundred ninety-seven million, eight hundred thousand, six hundred five".