21641994240 has 112 divisors (see below), whose sum is σ = 69250547808. Its totient is φ = 5771165696.

The previous prime is 21641994221. The next prime is 21641994287. The reversal of 21641994240 is 4249914612.

It is a junction number, because it is equal to n+sod(n) for n = 21641994192 and 21641994201.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34819 + ... + 210941.

Almost surely, 2^21641994240 is an apocalyptic number.

21641994240 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 21641994240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34625273904).

21641994240 is an abundant number, since it is smaller than the sum of its proper divisors (47608553568).

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

21641994240 is an equidigital number, since it uses as much as digits as its factorization.

21641994240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176157 (or 176133 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 42.

The spelling of 21641994240 in words is "twenty-one billion, six hundred forty-one million, nine hundred ninety-four thousand, two hundred forty".