21971359 has 2 divisors, whose sum is σ = 21971360. Its totient is φ = 21971358.

The previous prime is 21971351. The next prime is 21971387. The reversal of 21971359 is 95317912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21971359 - 2³ = 21971351 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21971351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10985679 + 10985680.

It is an arithmetic number, because the mean of its divisors is an integer number (10985680).

Almost surely, 2^21971359 is an apocalyptic number.

21971359 is a deficient number, since it is larger than the sum of its proper divisors (1).

21971359 is an equidigital number, since it uses as much as digits as its factorization.

21971359 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17010, while the sum is 37.

The square root of 21971359 is about 4687.3616246242. The cubic root of 21971359 is about 280.0822844899.

The spelling of 21971359 in words is "twenty-one million, nine hundred seventy-one thousand, three hundred fifty-nine".