21554509771 has 2 divisors, whose sum is σ = 21554509772. Its totient is φ = 21554509770.

The previous prime is 21554509751. The next prime is 21554509829. The reversal of 21554509771 is 17790545512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21554509771 - 2³³ = 12964575179 is a prime.

It is not a weakly prime, because it can be changed into another prime (21554509721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777254885 + 10777254886.

It is an arithmetic number, because the mean of its divisors is an integer number (10777254886).

Almost surely, 2^21554509771 is an apocalyptic number.

21554509771 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554509771 is an equidigital number, since it uses as much as digits as its factorization.

21554509771 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 441000, while the sum is 46.

The spelling of 21554509771 in words is "twenty-one billion, five hundred fifty-four million, five hundred nine thousand, seven hundred seventy-one".