821722 has 16 divisors (see below), whose sum is σ = 1378944. Its totient is φ = 364000.

The previous prime is 821677. The next prime is 821741. The reversal of 821722 is 227128.

821722 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 821693 and 821702.

It is an unprimeable number.

821722 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 447 + ... + 1357.

It is an arithmetic number, because the mean of its divisors is an integer number (86184).

2⁸²¹⁷²² is an apocalyptic number.

821722 is a gapful number since it is divisible by the number (82) formed by its first and last digit.

821722 is a deficient number, since it is larger than the sum of its proper divisors (557222).

821722 is a wasteful number, since it uses less digits than its factorization.

821722 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 965.

The product of its digits is 448, while the sum is 22.

The square root of 821722 is about 906.4888305986. The cubic root of 821722 is about 93.6644897327.

The spelling of 821722 in words is "eight hundred twenty-one thousand, seven hundred twenty-two".