21700291 has 2 divisors, whose sum is σ = 21700292. Its totient is φ = 21700290.

The previous prime is 21700253. The next prime is 21700297. The reversal of 21700291 is 19200712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21700291 - 2⁹ = 21699779 is a prime.

It is not a weakly prime, because it can be changed into another prime (21700297) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10850145 + 10850146.

It is an arithmetic number, because the mean of its divisors is an integer number (10850146).

Almost surely, 2^21700291 is an apocalyptic number.

21700291 is a deficient number, since it is larger than the sum of its proper divisors (1).

21700291 is an equidigital number, since it uses as much as digits as its factorization.

21700291 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 22.

The square root of 21700291 is about 4658.3571138332. The cubic root of 21700291 is about 278.9256920251.

The spelling of 21700291 in words is "twenty-one million, seven hundred thousand, two hundred ninety-one".