1291821618 has 16 divisors (see below), whose sum is σ = 2599495776. Its totient is φ = 427965120.

The previous prime is 1291821607. The next prime is 1291821623. The reversal of 1291821618 is 8161281921.

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 in 7 ways as a sum of consecutive naturals, for example, 659463 + ... + 661418.

It is an arithmetic number, because the mean of its divisors is an integer number (162468486).

Almost surely, 2^1291821618 is an apocalyptic number.

1291821618 is an abundant number, since it is smaller than the sum of its proper divisors (1307674158).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1291821618 is a wasteful number, since it uses less digits than its factorization.

1291821618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1321049.

The product of its digits is 13824, while the sum is 39.

The square root of 1291821618 is about 35941.9200655725. The cubic root of 1291821618 is about 1089.0993929962.

The spelling of 1291821618 in words is "one billion, two hundred ninety-one million, eight hundred twenty-one thousand, six hundred eighteen".