21793136640 has 448 divisors, whose sum is σ = 79493985792. Its totient is φ = 5046272000.

The previous prime is 21793136639. The next prime is 21793136647. The reversal of 21793136640 is 4663139712.

It is a junction number, because it is equal to n+sod(n) for n = 21793136592 and 21793136601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21793136647) 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, 31088290 + ... + 31088990.

Almost surely, 2^21793136640 is an apocalyptic number.

21793136640 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 21793136640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39746992896).

21793136640 is an abundant number, since it is smaller than the sum of its proper divisors (57700849152).

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

21793136640 is a wasteful number, since it uses less digits than its factorization.

21793136640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 769 (or 745 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 42.

The spelling of 21793136640 in words is "twenty-one billion, seven hundred ninety-three million, one hundred thirty-six thousand, six hundred forty".