821724868 has 12 divisors (see below), whose sum is σ = 1447670700. Its totient is φ = 408104672.

The previous prime is 821724859. The next prime is 821724877. The reversal of 821724868 is 868427128.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (821724859) and next prime (821724877).

It can be written as a sum of positive squares in 2 ways, for example, as 298321984 + 523402884 = 17272^2 + 22878^2 .

It is a super-3 number, since 3×821724868³ (a number of 28 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 688771 + ... + 689962.

It is an arithmetic number, because the mean of its divisors is an integer number (120639225).

Almost surely, 2^821724868 is an apocalyptic number.

It is an amenable number.

821724868 is a deficient number, since it is larger than the sum of its proper divisors (625945832).

821724868 is a wasteful number, since it uses less digits than its factorization.

821724868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1378886 (or 1378884 counting only the distinct ones).

The product of its digits is 344064, while the sum is 46.

The square root of 821724868 is about 28665.7438068507. The cubic root of 821724868 is about 936.6459870281.

The spelling of 821724868 in words is "eight hundred twenty-one million, seven hundred twenty-four thousand, eight hundred sixty-eight".