820532521721 has 8 divisors (see below), whose sum is σ = 895137156000. Its totient is φ = 745929682240.

The previous prime is 820532521663. The next prime is 820532521733. The reversal of 820532521721 is 127125235028.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 820532521721 - 2²⁶ = 820465412857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (820532521121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 617345 + ... + 1422033.

It is an arithmetic number, because the mean of its divisors is an integer number (111892144500).

Almost surely, 2^820532521721 is an apocalyptic number.

It is an amenable number.

820532521721 is a deficient number, since it is larger than the sum of its proper divisors (74604634279).

820532521721 is a wasteful number, since it uses less digits than its factorization.

820532521721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897399.

The product of its (nonzero) digits is 67200, while the sum is 38.

Adding to 820532521721 its reverse (127125235028), we get a palindrome (947657756749).

The spelling of 820532521721 in words is "eight hundred twenty billion, five hundred thirty-two million, five hundred twenty-one thousand, seven hundred twenty-one".