20871805780 has 72 divisors (see below), whose sum is σ = 51851167200. Its totient is φ = 7034739264.

The previous prime is 20871805727. The next prime is 20871805807. The reversal of 20871805780 is 8750817802.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 20871805780.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 122670 + ... + 238309.

It is an arithmetic number, because the mean of its divisors is an integer number (720155100).

Almost surely, 2^20871805780 is an apocalyptic number.

20871805780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20871805780 is an abundant number, since it is smaller than the sum of its proper divisors (30979361420).

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

20871805780 is a wasteful number, since it uses less digits than its factorization.

20871805780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 361061 (or 361052 counting only the distinct ones).

The product of its (nonzero) digits is 250880, while the sum is 46.

The spelling of 20871805780 in words is "twenty billion, eight hundred seventy-one million, eight hundred five thousand, seven hundred eighty".