1921678847 has 4 divisors (see below), whose sum is σ = 2096376936. Its totient is φ = 1746980760.

The previous prime is 1921678817. The next prime is 1921678849. The reversal of 1921678847 is 7488761291.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1921678847 - 2¹⁶ = 1921613311 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1921678849) 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, 87349028 + ... + 87349049.

It is an arithmetic number, because the mean of its divisors is an integer number (524094234).

Almost surely, 2^1921678847 is an apocalyptic number.

1921678847 is a deficient number, since it is larger than the sum of its proper divisors (174698089).

1921678847 is a wasteful number, since it uses less digits than its factorization.

1921678847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 174698088.

The product of its digits is 1354752, while the sum is 53.

The square root of 1921678847 is about 43836.9575472569. The cubic root of 1921678847 is about 1243.2551585103.

The spelling of 1921678847 in words is "one billion, nine hundred twenty-one million, six hundred seventy-eight thousand, eight hundred forty-seven".