820811556221952 has 352 divisors, whose sum is σ = 2377504886272000. Its totient is φ = 250809517670400.

The previous prime is 820811556221897. The next prime is 820811556221981. The reversal of 820811556221952 is 259122655118028.

It is a super-2 number, since 2×820811556221952² (a number of 31 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is a junction number, because it is equal to n+sod(n) for n = 820811556221892 and 820811556221901.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16373307927 + ... + 16373358057.

Almost surely, 2^{820811556221952} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 820811556221952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1188752443136000).

820811556221952 is an abundant number, since it is smaller than the sum of its proper divisors (1556693330050048).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

820811556221952 is a wasteful number, since it uses less digits than its factorization.

820811556221952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59253 (or 59235 counting only the distinct ones).

The product of its (nonzero) digits is 6912000, while the sum is 57.

The spelling of 820811556221952 in words is "eight hundred twenty trillion, eight hundred eleven billion, five hundred fifty-six million, two hundred twenty-one thousand, nine hundred fifty-two".