20865777660 has 576 divisors, whose sum is σ = 81459302400. Its totient is φ = 4341123072.

The previous prime is 20865777659. The next prime is 20865777671. The reversal of 20865777660 is 6677756802.

20865777660 is a `hidden beast` number, since 2 + 0 + 8 + 6 + 577 + 7 + 6 + 60 = 666.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a junction number, because it is equal to n+sod(n) for n = 20865777597 and 20865777606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 56854797 + ... + 56855163.

It is an arithmetic number, because the mean of its divisors is an integer number (141422400).

Almost surely, 2^20865777660 is an apocalyptic number.

20865777660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20865777660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40729651200).

20865777660 is an abundant number, since it is smaller than the sum of its proper divisors (60593524740).

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

20865777660 is a wasteful number, since it uses less digits than its factorization.

20865777660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 507 (or 486 counting only the distinct ones).

The product of its (nonzero) digits is 5927040, while the sum is 54.

The spelling of 20865777660 in words is "twenty billion, eight hundred sixty-five million, seven hundred seventy-seven thousand, six hundred sixty".