21380128794 has 64 divisors (see below), whose sum is σ = 49085153280. Its totient is φ = 6891032880.

The previous prime is 21380128789. The next prime is 21380128799. The reversal of 21380128794 is 49782108312.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21380128789) and next prime (21380128799).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21380128799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2283687 + ... + 2293029.

It is an arithmetic number, because the mean of its divisors is an integer number (766955520).

Almost surely, 2^21380128794 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21380128794, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24542576640).

21380128794 is an abundant number, since it is smaller than the sum of its proper divisors (27705024486).

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

21380128794 is a wasteful number, since it uses less digits than its factorization.

21380128794 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10752 (or 10746 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The spelling of 21380128794 in words is "twenty-one billion, three hundred eighty million, one hundred twenty-eight thousand, seven hundred ninety-four".