21864650820 has 48 divisors (see below), whose sum is σ = 61232189760. Its totient is φ = 5829510016.

The previous prime is 21864650807. The next prime is 21864650831. The reversal of 21864650820 is 2805646812.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 331519 + ... + 391961.

It is an arithmetic number, because the mean of its divisors is an integer number (1275670620).

Almost surely, 2^21864650820 is an apocalyptic number.

21864650820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21864650820 is an abundant number, since it is smaller than the sum of its proper divisors (39367538940).

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

21864650820 is a wasteful number, since it uses less digits than its factorization.

21864650820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66484 (or 66482 counting only the distinct ones).

The product of its (nonzero) digits is 184320, while the sum is 42.

The spelling of 21864650820 in words is "twenty-one billion, eight hundred sixty-four million, six hundred fifty thousand, eight hundred twenty".