1221575989 has 4 divisors (see below), whose sum is σ = 1236293856. Its totient is φ = 1206858124.

The previous prime is 1221575963. The next prime is 1221576007. The reversal of 1221575989 is 9895751221.

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: 9895751221 = 17 ⋅582103013.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1221575989 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221575939) 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, 7358809 + ... + 7358974.

It is an arithmetic number, because the mean of its divisors is an integer number (309073464).

Almost surely, 2^1221575989 is an apocalyptic number.

It is an amenable number.

1221575989 is a deficient number, since it is larger than the sum of its proper divisors (14717867).

1221575989 is an equidigital number, since it uses as much as digits as its factorization.

1221575989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14717866.

The product of its digits is 453600, while the sum is 49.

The square root of 1221575989 is about 34951.0513289658. The cubic root of 1221575989 is about 1068.9896390280.

The spelling of 1221575989 in words is "one billion, two hundred twenty-one million, five hundred seventy-five thousand, nine hundred eighty-nine".