20975551 has 2 divisors, whose sum is σ = 20975552. Its totient is φ = 20975550.

The previous prime is 20975533. The next prime is 20975557. The reversal of 20975551 is 15557902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20975551 - 2⁵ = 20975519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20975557) 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, 10487775 + 10487776.

It is an arithmetic number, because the mean of its divisors is an integer number (10487776).

Almost surely, 2^20975551 is an apocalyptic number.

20975551 is a deficient number, since it is larger than the sum of its proper divisors (1).

20975551 is an equidigital number, since it uses as much as digits as its factorization.

20975551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15750, while the sum is 34.

The square root of 20975551 is about 4579.9073134726. The cubic root of 20975551 is about 275.7853079060.

The spelling of 20975551 in words is "twenty million, nine hundred seventy-five thousand, five hundred fifty-one".