1261543198 has 4 divisors (see below), whose sum is σ = 1892314800. Its totient is φ = 630771598.

The previous prime is 1261543163. The next prime is 1261543207. The reversal of 1261543198 is 8913451621.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 1261543198.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315385798 + ... + 315385801.

It is an arithmetic number, because the mean of its divisors is an integer number (473078700).

Almost surely, 2^1261543198 is an apocalyptic number.

1261543198 is a deficient number, since it is larger than the sum of its proper divisors (630771602).

1261543198 is an equidigital number, since it uses as much as digits as its factorization.

1261543198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 630771601.

The product of its digits is 51840, while the sum is 40.

The square root of 1261543198 is about 35518.2093861726. The cubic root of 1261543198 is about 1080.5230656723.

The spelling of 1261543198 in words is "one billion, two hundred sixty-one million, five hundred forty-three thousand, one hundred ninety-eight".