1198731561 has 4 divisors (see below), whose sum is σ = 1598308752. Its totient is φ = 799154372.

The previous prime is 1198731551. The next prime is 1198731601. The reversal of 1198731561 is 1651378911.

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 1198731561 - 2⁷ = 1198731433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1198731551) 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, 199788591 + ... + 199788596.

It is an arithmetic number, because the mean of its divisors is an integer number (399577188).

Almost surely, 2^1198731561 is an apocalyptic number.

It is an amenable number.

1198731561 is a deficient number, since it is larger than the sum of its proper divisors (399577191).

1198731561 is an equidigital number, since it uses as much as digits as its factorization.

1198731561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399577190.

The product of its digits is 45360, while the sum is 42.

The square root of 1198731561 is about 34622.7029707387. The cubic root of 1198731561 is about 1062.2840156318.

The spelling of 1198731561 in words is "one billion, one hundred ninety-eight million, seven hundred thirty-one thousand, five hundred sixty-one".