21554550497 has 2 divisors, whose sum is σ = 21554550498. Its totient is φ = 21554550496.

The previous prime is 21554550439. The next prime is 21554550499. The reversal of 21554550497 is 79405545512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21213631201 + 340919296 = 145649^2 + 18464^2 .

It is a cyclic number.

It is not a de Polignac number, because 21554550497 - 2¹² = 21554546401 is a prime.

Together with 21554550499, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21554550499) 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, 10777275248 + 10777275249.

It is an arithmetic number, because the mean of its divisors is an integer number (10777275249).

Almost surely, 2^21554550497 is an apocalyptic number.

It is an amenable number.

21554550497 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554550497 is an equidigital number, since it uses as much as digits as its factorization.

21554550497 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1260000, while the sum is 47.

The spelling of 21554550497 in words is "twenty-one billion, five hundred fifty-four million, five hundred fifty thousand, four hundred ninety-seven".