978721 has 4 divisors (see below), whose sum is σ = 1012500. Its totient is φ = 944944.

The previous prime is 978713. The next prime is 978727. The reversal of 978721 is 127879.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127879 = 41 ⋅3119.

It can be written as a sum of positive squares in 2 ways, for example, as 739600 + 239121 = 860^2 + 489^2 .

It is a cyclic number.

It is not a de Polignac number, because 978721 - 2³ = 978713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (978727) 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, 16846 + ... + 16903.

It is an arithmetic number, because the mean of its divisors is an integer number (253125).

2⁹⁷⁸⁷²¹ is an apocalyptic number.

It is an amenable number.

978721 is a deficient number, since it is larger than the sum of its proper divisors (33779).

978721 is a wasteful number, since it uses less digits than its factorization.

978721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33778.

The product of its digits is 7056, while the sum is 34.

The square root of 978721 is about 989.3032901997. The cubic root of 978721 is about 99.2856086024.

The spelling of 978721 in words is "nine hundred seventy-eight thousand, seven hundred twenty-one".