820961640 has 96 divisors (see below), whose sum is σ = 2705788800. Its totient is φ = 215832960.

The previous prime is 820961629. The next prime is 820961641. The reversal of 820961640 is 46169028.

820961640 is a `hidden beast` number, since 8 + 2 + 0 + 9 + 6 + 1 + 640 = 666.

820961640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 820961595 and 820961604.

It is not an unprimeable number, because it can be changed into a prime (820961641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9501 + ... + 41619.

It is an arithmetic number, because the mean of its divisors is an integer number (28185300).

Almost surely, 2^820961640 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 820961640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1352894400).

820961640 is an abundant number, since it is smaller than the sum of its proper divisors (1884827160).

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

820961640 is a wasteful number, since it uses less digits than its factorization.

820961640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32207 (or 32200 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 820961640 is about 28652.4281693542. The cubic root of 820961640 is about 936.3559078246.

The spelling of 820961640 in words is "eight hundred twenty million, nine hundred sixty-one thousand, six hundred forty".