978439821 has 4 divisors (see below), whose sum is σ = 1304586432. Its totient is φ = 652293212.

The previous prime is 978439783. The next prime is 978439829. The reversal of 978439821 is 128934879.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 978439821 - 2²¹ = 976342669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (978439829) 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, 163073301 + ... + 163073306.

It is an arithmetic number, because the mean of its divisors is an integer number (326146608).

Almost surely, 2^978439821 is an apocalyptic number.

It is an amenable number.

978439821 is a deficient number, since it is larger than the sum of its proper divisors (326146611).

978439821 is a wasteful number, since it uses less digits than its factorization.

978439821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 326146610.

The product of its digits is 870912, while the sum is 51.

The square root of 978439821 is about 31280.0227141861. The cubic root of 978439821 is about 992.7609969504.

The spelling of 978439821 in words is "nine hundred seventy-eight million, four hundred thirty-nine thousand, eight hundred twenty-one".