820687563540 has 432 divisors, whose sum is σ = 2811127322640. Its totient is φ = 192640757760.

The previous prime is 820687563499. The next prime is 820687563587. The reversal of 820687563540 is 45365786028.

820687563540 is a `hidden beast` number, since 8 + 20 + 6 + 8 + 7 + 563 + 54 + 0 = 666.

820687563540 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 11616097284 + 809071466256 = 107778^2 + 899484^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 506283930 + ... + 506285550.

Almost surely, 2^820687563540 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 820687563540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1405563661320).

820687563540 is an abundant number, since it is smaller than the sum of its proper divisors (1990439759100).

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

820687563540 is a wasteful number, since it uses less digits than its factorization.

820687563540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2104 (or 2076 counting only the distinct ones).

The product of its (nonzero) digits is 9676800, while the sum is 54.

The spelling of 820687563540 in words is "eight hundred twenty billion, six hundred eighty-seven million, five hundred sixty-three thousand, five hundred forty".