21361988920 has 64 divisors (see below), whose sum is σ = 50381987040. Its totient is φ = 8142489600.

The previous prime is 21361988863. The next prime is 21361988929. The reversal of 21361988920 is 2988916312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361988929) 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, 80941 + ... + 221980.

Almost surely, 2^21361988920 is an apocalyptic number.

21361988920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21361988920 is an abundant number, since it is smaller than the sum of its proper divisors (29019998120).

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

21361988920 is a wasteful number, since it uses less digits than its factorization.

21361988920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 303016 (or 303012 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 49.

The spelling of 21361988920 in words is "twenty-one billion, three hundred sixty-one million, nine hundred eighty-eight thousand, nine hundred twenty".