1208116721 has 4 divisors (see below), whose sum is σ = 1380704832. Its totient is φ = 1035528612.

The previous prime is 1208116703. The next prime is 1208116733. The reversal of 1208116721 is 1276118021.

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: 1276118021 = 59 ⋅21629119.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1208116721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1208116321) 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, 86294045 + ... + 86294058.

It is an arithmetic number, because the mean of its divisors is an integer number (345176208).

Almost surely, 2^1208116721 is an apocalyptic number.

It is an amenable number.

1208116721 is a deficient number, since it is larger than the sum of its proper divisors (172588111).

1208116721 is an equidigital number, since it uses as much as digits as its factorization.

1208116721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172588110.

The product of its (nonzero) digits is 1344, while the sum is 29.

The square root of 1208116721 is about 34757.9734881077. The cubic root of 1208116721 is about 1065.0491049823.

The spelling of 1208116721 in words is "one billion, two hundred eight million, one hundred sixteen thousand, seven hundred twenty-one".