8219847921 has 16 divisors (see below), whose sum is σ = 11071515840. Its totient is φ = 5424168960.

The previous prime is 8219847913. The next prime is 8219847959. The reversal of 8219847921 is 1297489128.

It is a happy number.

It is not a de Polignac number, because 8219847921 - 2³ = 8219847913 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (8219847971) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 244926 + ... + 276456.

It is an arithmetic number, because the mean of its divisors is an integer number (691969740).

Almost surely, 2^8219847921 is an apocalyptic number.

It is an amenable number.

8219847921 is a deficient number, since it is larger than the sum of its proper divisors (2851667919).

8219847921 is a wasteful number, since it uses less digits than its factorization.

8219847921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32416.

The product of its digits is 580608, while the sum is 51.

The square root of 8219847921 is about 90663.3769556374. The cubic root of 8219847921 is about 2018.1553529701.

The spelling of 8219847921 in words is "eight billion, two hundred nineteen million, eight hundred forty-seven thousand, nine hundred twenty-one".