21657683380 has 48 divisors (see below), whose sum is σ = 46957510656. Its totient is φ = 8385189120.

The previous prime is 21657683371. The next prime is 21657683381. The reversal of 21657683380 is 8338675612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21657683381) 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, 157 + ... + 208123.

It is an arithmetic number, because the mean of its divisors is an integer number (978281472).

Almost surely, 2^21657683380 is an apocalyptic number.

21657683380 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 21657683380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23478755328).

21657683380 is an abundant number, since it is smaller than the sum of its proper divisors (25299827276).

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

21657683380 is a wasteful number, since it uses less digits than its factorization.

21657683380 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208144 (or 208142 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 49.

The spelling of 21657683380 in words is "twenty-one billion, six hundred fifty-seven million, six hundred eighty-three thousand, three hundred eighty".