21788293 has 2 divisors, whose sum is σ = 21788294. Its totient is φ = 21788292.

The previous prime is 21788233. The next prime is 21788297. The reversal of 21788293 is 39288712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20268004 + 1520289 = 4502^2 + 1233^2 .

It is a cyclic number.

It is not a de Polignac number, because 21788293 - 2¹⁷ = 21657221 is a prime.

It is equal to p_1376689 and since 21788293 and 1376689 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21788297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10894146 + 10894147.

It is an arithmetic number, because the mean of its divisors is an integer number (10894147).

Almost surely, 2^21788293 is an apocalyptic number.

It is an amenable number.

21788293 is a deficient number, since it is larger than the sum of its proper divisors (1).

21788293 is an equidigital number, since it uses as much as digits as its factorization.

21788293 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 40.

The square root of 21788293 is about 4667.7931616557. The cubic root of 21788293 is about 279.3022294105.

The spelling of 21788293 in words is "twenty-one million, seven hundred eighty-eight thousand, two hundred ninety-three".