21898681920 has 336 divisors, whose sum is σ = 80063858160. Its totient is φ = 5474746368.

The previous prime is 21898681807. The next prime is 21898681943. The reversal of 21898681920 is 2918689812.

It can be written as a sum of positive squares in 8 ways, for example, as 5737153536 + 16161528384 = 75744^2 + 127128^2 .

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 15323766 + ... + 15325194.

Almost surely, 2^21898681920 is an apocalyptic number.

21898681920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21898681920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40031929080).

21898681920 is an abundant number, since it is smaller than the sum of its proper divisors (58165176240).

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

21898681920 is a wasteful number, since it uses less digits than its factorization.

21898681920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1782 (or 1769 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 54.

The spelling of 21898681920 in words is "twenty-one billion, eight hundred ninety-eight million, six hundred eighty-one thousand, nine hundred twenty".