1220802721 has 4 divisors (see below), whose sum is σ = 1236256000. Its totient is φ = 1205349444.

The previous prime is 1220802719. The next prime is 1220802773. The reversal of 1220802721 is 1272080221.

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.

It is a cyclic number.

It is not a de Polignac number, because 1220802721 - 2¹ = 1220802719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1220809721) 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, 7726521 + ... + 7726678.

It is an arithmetic number, because the mean of its divisors is an integer number (309064000).

Almost surely, 2^1220802721 is an apocalyptic number.

It is an amenable number.

1220802721 is a deficient number, since it is larger than the sum of its proper divisors (15453279).

1220802721 is an equidigital number, since it uses as much as digits as its factorization.

1220802721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15453278.

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 1220802721 is about 34939.9874212914. The cubic root of 1220802721 is about 1068.7640315703.

Adding to 1220802721 its reverse (1272080221), we get a palindrome (2492882942).

The spelling of 1220802721 in words is "one billion, two hundred twenty million, eight hundred two thousand, seven hundred twenty-one".