1215989 has 4 divisors (see below), whose sum is σ = 1224300. Its totient is φ = 1207680.

The previous prime is 1215923. The next prime is 1216009. The reversal of 1215989 is 9895121.

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 280900 + 935089 = 530^2 + 967^2 .

It is a cyclic number.

It is not a de Polignac number, because 1215989 - 2²⁰ = 167413 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 (1215919) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3932 + ... + 4229.

It is an arithmetic number, because the mean of its divisors is an integer number (306075).

2^1215989 is an apocalyptic number.

It is an amenable number.

1215989 is a deficient number, since it is larger than the sum of its proper divisors (8311).

1215989 is an equidigital number, since it uses as much as digits as its factorization.

1215989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8310.

The product of its digits is 6480, while the sum is 35.

The square root of 1215989 is about 1102.7189125067. The cubic root of 1215989 is about 106.7357441012.

The spelling of 1215989 in words is "one million, two hundred fifteen thousand, nine hundred eighty-nine".