21788297 has 2 divisors, whose sum is σ = 21788298. Its totient is φ = 21788296.

The previous prime is 21788293. The next prime is 21788341. The reversal of 21788297 is 79288712.

It is an a-pointer prime, because the next prime (21788341) can be obtained adding 21788297 to its sum of digits (44).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12418576 + 9369721 = 3524^2 + 3061^2 .

It is a cyclic number.

It is not a de Polignac number, because 21788297 - 2² = 21788293 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21788293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10894148 + 10894149.

It is an arithmetic number, because the mean of its divisors is an integer number (10894149).

Almost surely, 2^21788297 is an apocalyptic number.

It is an amenable number.

21788297 is a deficient number, since it is larger than the sum of its proper divisors (1).

21788297 is an equidigital number, since it uses as much as digits as its factorization.

21788297 is an evil number, because the sum of its binary digits is even.

The product of its digits is 112896, while the sum is 44.

The square root of 21788297 is about 4667.7935901237. The cubic root of 21788297 is about 279.3022465024.

The spelling of 21788297 in words is "twenty-one million, seven hundred eighty-eight thousand, two hundred ninety-seven".