1186398721 has 4 divisors (see below), whose sum is σ = 1187032000. Its totient is φ = 1185765444.

The previous prime is 1186398691. The next prime is 1186398751. The reversal of 1186398721 is 1278936811.

It is a happy number.

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: 1278936811 = 6607 ⋅193573.

It is an interprime number because it is at equal distance from previous prime (1186398691) and next prime (1186398751).

It is a cyclic number.

It is not a de Polignac number, because 1186398721 - 2⁷ = 1186398593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1186398751) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 313821 + ... + 317578.

It is an arithmetic number, because the mean of its divisors is an integer number (296758000).

Almost surely, 2^1186398721 is an apocalyptic number.

It is an amenable number.

1186398721 is a deficient number, since it is larger than the sum of its proper divisors (633279).

1186398721 is an equidigital number, since it uses as much as digits as its factorization.

1186398721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 633278.

The product of its digits is 145152, while the sum is 46.

The square root of 1186398721 is about 34444.1391386111. The cubic root of 1186398721 is about 1058.6284387763.

The spelling of 1186398721 in words is "one billion, one hundred eighty-six million, three hundred ninety-eight thousand, seven hundred twenty-one".