821328761 has 6 divisors (see below), whose sum is σ = 902782986. Its totient is φ = 746662400.

The previous prime is 821328743. The next prime is 821328763. The reversal of 821328761 is 167823128.

It can be written as a sum of positive squares in only one way, i.e., 446519161 + 374809600 = 21131^2 + 19360^2 .

It is not a de Polignac number, because 821328761 - 2¹⁴ = 821312377 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821328763) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3393800 + ... + 3394041.

It is an arithmetic number, because the mean of its divisors is an integer number (150463831).

Almost surely, 2^821328761 is an apocalyptic number.

It is an amenable number.

821328761 is a deficient number, since it is larger than the sum of its proper divisors (81454225).

821328761 is a wasteful number, since it uses less digits than its factorization.

821328761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6787863 (or 6787852 counting only the distinct ones).

The product of its digits is 32256, while the sum is 38.

The square root of 821328761 is about 28658.8339085874. The cubic root of 821328761 is about 936.4954615189.

The spelling of 821328761 in words is "eight hundred twenty-one million, three hundred twenty-eight thousand, seven hundred sixty-one".