21980435856 has 160 divisors (see below), whose sum is σ = 60338995200. Its totient is φ = 6883484160.

The previous prime is 21980435843. The next prime is 21980435857. The reversal of 21980435856 is 65853408912.

It is a junction number, because it is equal to n+sod(n) for n = 21980435799 and 21980435808.

It is not an unprimeable number, because it can be changed into a prime (21980435857) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12495105 + ... + 12496863.

It is an arithmetic number, because the mean of its divisors is an integer number (377118720).

Almost surely, 2^21980435856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21980435856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30169497600).

21980435856 is an abundant number, since it is smaller than the sum of its proper divisors (38358559344).

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

21980435856 is a wasteful number, since it uses less digits than its factorization.

21980435856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2037 (or 2031 counting only the distinct ones).

The product of its (nonzero) digits is 2073600, while the sum is 51.

The spelling of 21980435856 in words is "twenty-one billion, nine hundred eighty million, four hundred thirty-five thousand, eight hundred fifty-six".