821681313 has 8 divisors (see below), whose sum is σ = 1116246528. Its totient is φ = 537451824.

The previous prime is 821681309. The next prime is 821681339. The reversal of 821681313 is 313186128.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 821681313 - 2² = 821681309 is a prime.

It is not an unprimeable number, because it can be changed into a prime (821681303) 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, 2583745 + ... + 2584062.

It is an arithmetic number, because the mean of its divisors is an integer number (139530816).

Almost surely, 2^821681313 is an apocalyptic number.

It is an amenable number.

821681313 is a deficient number, since it is larger than the sum of its proper divisors (294565215).

821681313 is a wasteful number, since it uses less digits than its factorization.

821681313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5167863.

The product of its digits is 6912, while the sum is 33.

The square root of 821681313 is about 28664.9840920940. The cubic root of 821681313 is about 936.6294379623.

The spelling of 821681313 in words is "eight hundred twenty-one million, six hundred eighty-one thousand, three hundred thirteen".