1921615778841 has 16 divisors (see below), whose sum is σ = 2854547232768. Its totient is φ = 1139836566800.

The previous prime is 1921615778807. The next prime is 1921615778843. The reversal of 1921615778841 is 1488775161291.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1921615778841 - 2¹⁷ = 1921615647769 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1921615778843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 619474845 + ... + 619477946.

It is an arithmetic number, because the mean of its divisors is an integer number (178409202048).

Almost surely, 2^{1921615778841} is an apocalyptic number.

1921615778841 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1921615778841 is a deficient number, since it is larger than the sum of its proper divisors (932931453927).

1921615778841 is a wasteful number, since it uses less digits than its factorization.

1921615778841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1238952852.

The product of its digits is 6773760, while the sum is 60.

The spelling of 1921615778841 in words is "one trillion, nine hundred twenty-one billion, six hundred fifteen million, seven hundred seventy-eight thousand, eight hundred forty-one".