21808741780 has 48 divisors (see below), whose sum is σ = 52350480000. Its totient is φ = 7475925888.

The previous prime is 21808741741. The next prime is 21808741789. The reversal of 21808741780 is 8714780812.

It is a self number, because there is not a number n which added to its sum of digits gives 21808741780.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808741789) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1039474 + ... + 1060246.

It is an arithmetic number, because the mean of its divisors is an integer number (1090635000).

Almost surely, 2^21808741780 is an apocalyptic number.

21808741780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21808741780 is an abundant number, since it is smaller than the sum of its proper divisors (30541738220).

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

21808741780 is a wasteful number, since it uses less digits than its factorization.

21808741780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28288 (or 28286 counting only the distinct ones).

The product of its (nonzero) digits is 200704, while the sum is 46.

The spelling of 21808741780 in words is "twenty-one billion, eight hundred eight million, seven hundred forty-one thousand, seven hundred eighty".