21582775477 has 2 divisors, whose sum is σ = 21582775478. Its totient is φ = 21582775476.

The previous prime is 21582775421. The next prime is 21582775481. The reversal of 21582775477 is 77457728512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17900834436 + 3681941041 = 133794^2 + 60679^2 .

It is a cyclic number.

It is not a de Polignac number, because 21582775477 - 2⁷ = 21582775349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21582773477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10791387738 + 10791387739.

It is an arithmetic number, because the mean of its divisors is an integer number (10791387739).

Almost surely, 2^21582775477 is an apocalyptic number.

It is an amenable number.

21582775477 is a deficient number, since it is larger than the sum of its proper divisors (1).

21582775477 is an equidigital number, since it uses as much as digits as its factorization.

21582775477 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7683200, while the sum is 55.

The spelling of 21582775477 in words is "twenty-one billion, five hundred eighty-two million, seven hundred seventy-five thousand, four hundred seventy-seven".