21780728794893 has 32 divisors (see below), whose sum is σ = 30101177957760. Its totient is φ = 13992363795200.

The previous prime is 21780728794873. The next prime is 21780728794901. The reversal of 21780728794893 is 39849782708712.

It is a cyclic number.

It is not a de Polignac number, because 21780728794893 - 2⁶ = 21780728794829 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21780728794873) 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, 116208571 + ... + 116395847.

It is an arithmetic number, because the mean of its divisors is an integer number (940661811180).

Almost surely, 2^{21780728794893} is an apocalyptic number.

It is an amenable number.

21780728794893 is a deficient number, since it is larger than the sum of its proper divisors (8320449162867).

21780728794893 is a wasteful number, since it uses less digits than its factorization.

21780728794893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189917.

The product of its (nonzero) digits is 682795008, while the sum is 75.

The spelling of 21780728794893 in words is "twenty-one trillion, seven hundred eighty billion, seven hundred twenty-eight million, seven hundred ninety-four thousand, eight hundred ninety-three".