20995591 has 2 divisors, whose sum is σ = 20995592. Its totient is φ = 20995590.

The previous prime is 20995571. The next prime is 20995609. The reversal of 20995591 is 19559902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20995591 - 2¹¹ = 20993543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20995571) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10497795 + 10497796.

It is an arithmetic number, because the mean of its divisors is an integer number (10497796).

Almost surely, 2^20995591 is an apocalyptic number.

20995591 is a deficient number, since it is larger than the sum of its proper divisors (1).

20995591 is an equidigital number, since it uses as much as digits as its factorization.

20995591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36450, while the sum is 40.

The square root of 20995591 is about 4582.0946083642. The cubic root of 20995591 is about 275.8731081967.

The spelling of 20995591 in words is "twenty million, nine hundred ninety-five thousand, five hundred ninety-one".