21564733746553 has 2 divisors, whose sum is σ = 21564733746554. Its totient is φ = 21564733746552.

The previous prime is 21564733746511. The next prime is 21564733746557. The reversal of 21564733746553 is 35564733746512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21547718370304 + 17015376249 = 4641952^2 + 130443^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21564733746553 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21564733746491 and 21564733746500.

It is not a weakly prime, because it can be changed into another prime (21564733746557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10782366873276 + 10782366873277.

It is an arithmetic number, because the mean of its divisors is an integer number (10782366873277).

Almost surely, 2^{21564733746553} is an apocalyptic number.

It is an amenable number.

21564733746553 is a deficient number, since it is larger than the sum of its proper divisors (1).

21564733746553 is an equidigital number, since it uses as much as digits as its factorization.

21564733746553 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 190512000, while the sum is 61.

The spelling of 21564733746553 in words is "twenty-one trillion, five hundred sixty-four billion, seven hundred thirty-three million, seven hundred forty-six thousand, five hundred fifty-three".