1215647989 has 4 divisors (see below), whose sum is σ = 1216181824. Its totient is φ = 1215114156.

The previous prime is 1215647929. The next prime is 1215648001. The reversal of 1215647989 is 9897465121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9897465121 = 563 ⋅17579867.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1215647989 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 (1215647929) 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, 263487 + ... + 268060.

It is an arithmetic number, because the mean of its divisors is an integer number (304045456).

Almost surely, 2^1215647989 is an apocalyptic number.

It is an amenable number.

1215647989 is a deficient number, since it is larger than the sum of its proper divisors (533835).

1215647989 is an equidigital number, since it uses as much as digits as its factorization.

1215647989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533834.

The product of its digits is 1088640, while the sum is 52.

The square root of 1215647989 is about 34866.1438791272. The cubic root of 1215647989 is about 1067.2576553895.

The spelling of 1215647989 in words is "one billion, two hundred fifteen million, six hundred forty-seven thousand, nine hundred eighty-nine".