21810235840 has 56 divisors (see below), whose sum is σ = 52062918480. Its totient is φ = 8702711808.

The previous prime is 21810235807. The next prime is 21810235849. The reversal of 21810235840 is 4853201812.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21810235796 and 21810235805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21810235849) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47559 + ... + 214201.

Almost surely, 2^21810235840 is an apocalyptic number.

21810235840 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 21810235840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26031459240).

21810235840 is an abundant number, since it is smaller than the sum of its proper divisors (30252682640).

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

21810235840 is a wasteful number, since it uses less digits than its factorization.

21810235840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167069 (or 167059 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 34.

The spelling of 21810235840 in words is "twenty-one billion, eight hundred ten million, two hundred thirty-five thousand, eight hundred forty".