1221473728 has 14 divisors (see below), whose sum is σ = 2423862056. Its totient is φ = 610736832.

The previous prime is 1221473723. The next prime is 1221473731. The reversal of 1221473728 is 8273741221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221473723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9542700 + ... + 9542827.

It is an arithmetic number, because the mean of its divisors is an integer number (173133004).

Almost surely, 2^1221473728 is an apocalyptic number.

It is an amenable number.

1221473728 is a deficient number, since it is larger than the sum of its proper divisors (1202388328).

1221473728 is an equidigital number, since it uses as much as digits as its factorization.

1221473728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19085539 (or 19085529 counting only the distinct ones).

The product of its digits is 37632, while the sum is 37.

The square root of 1221473728 is about 34949.5883809810. The cubic root of 1221473728 is about 1068.9598089830.

The spelling of 1221473728 in words is "one billion, two hundred twenty-one million, four hundred seventy-three thousand, seven hundred twenty-eight".