821978 has 16 divisors (see below), whose sum is σ = 1317120. Its totient is φ = 383616.

The previous prime is 821971. The next prime is 821993. The reversal of 821978 is 879128.

It is a happy number.

821978 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (821971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3575 + ... + 3797.

It is an arithmetic number, because the mean of its divisors is an integer number (82320).

2⁸²¹⁹⁷⁸ is an apocalyptic number.

821978 is a deficient number, since it is larger than the sum of its proper divisors (495142).

821978 is a wasteful number, since it uses less digits than its factorization.

821978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341.

The product of its digits is 8064, while the sum is 35.

The square root of 821978 is about 906.6300237693. The cubic root of 821978 is about 93.6742154955.

The spelling of 821978 in words is "eight hundred twenty-one thousand, nine hundred seventy-eight".