21765803980 has 24 divisors (see below), whose sum is σ = 45784267200. Its totient is φ = 8691830400.

The previous prime is 21765803977. The next prime is 21765803981. The reversal of 21765803980 is 8930856712.

It is a hoax number, since the sum of its digits (49) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21765803981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 893380 + ... + 917419.

It is an arithmetic number, because the mean of its divisors is an integer number (1907677800).

Almost surely, 2^21765803980 is an apocalyptic number.

21765803980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21765803980 is an abundant number, since it is smaller than the sum of its proper divisors (24018463220).

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

21765803980 is a wasteful number, since it uses less digits than its factorization.

21765803980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1811409 (or 1811407 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 21765803980 in words is "twenty-one billion, seven hundred sixty-five million, eight hundred three thousand, nine hundred eighty".