1164778721 has 4 divisors (see below), whose sum is σ = 1186755732. Its totient is φ = 1142801712.

The previous prime is 1164778709. The next prime is 1164778733. The reversal of 1164778721 is 1278774611.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1278774611 = 167 ⋅7657333.

It is an interprime number because it is at equal distance from previous prime (1164778709) and next prime (1164778733).

It can be written as a sum of positive squares in 2 ways, for example, as 456420496 + 708358225 = 21364^2 + 26615^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1164778721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1164778751) 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, 10988426 + ... + 10988531.

It is an arithmetic number, because the mean of its divisors is an integer number (296688933).

Almost surely, 2^1164778721 is an apocalyptic number.

It is an amenable number.

1164778721 is a deficient number, since it is larger than the sum of its proper divisors (21977011).

1164778721 is an equidigital number, since it uses as much as digits as its factorization.

1164778721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21977010.

The product of its digits is 131712, while the sum is 44.

The square root of 1164778721 is about 34128.8546687404. The cubic root of 1164778721 is about 1052.1584385622.

The spelling of 1164778721 in words is "one billion, one hundred sixty-four million, seven hundred seventy-eight thousand, seven hundred twenty-one".