1988645 has 4 divisors (see below), whose sum is σ = 2386380. Its totient is φ = 1590912.

The previous prime is 1988633. The next prime is 1988653. The reversal of 1988645 is 5468891.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 638401 + 1350244 = 799^2 + 1162^2 .

It is a cyclic number.

It is not a de Polignac number, because 1988645 - 2¹⁰ = 1987621 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198860 + ... + 198869.

It is an arithmetic number, because the mean of its divisors is an integer number (596595).

2^1988645 is an apocalyptic number.

It is an amenable number.

1988645 is a deficient number, since it is larger than the sum of its proper divisors (397735).

1988645 is an equidigital number, since it uses as much as digits as its factorization.

1988645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397734.

The product of its digits is 69120, while the sum is 41.

The square root of 1988645 is about 1410.1932491684. The cubic root of 1988645 is about 125.7532122543.

The spelling of 1988645 in words is "one million, nine hundred eighty-eight thousand, six hundred forty-five".