1989815 has 4 divisors (see below), whose sum is σ = 2387784. Its totient is φ = 1591848.

The previous prime is 1989811. The next prime is 1989847. The reversal of 1989815 is 5189891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5189891 = 7 ⋅741413.

It is a cyclic number.

It is not a de Polignac number, because 1989815 - 2² = 1989811 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1989811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198977 + ... + 198986.

It is an arithmetic number, because the mean of its divisors is an integer number (596946).

2^1989815 is an apocalyptic number.

1989815 is a deficient number, since it is larger than the sum of its proper divisors (397969).

1989815 is an equidigital number, since it uses as much as digits as its factorization.

1989815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 397968.

The product of its digits is 25920, while the sum is 41.

The square root of 1989815 is about 1410.6080249311. The cubic root of 1989815 is about 125.7778693136. Note that the first 3 decimals are identical.

The spelling of 1989815 in words is "one million, nine hundred eighty-nine thousand, eight hundred fifteen".