21450035212561 has 2 divisors, whose sum is σ = 21450035212562. Its totient is φ = 21450035212560.

The previous prime is 21450035212523. The next prime is 21450035212607. The reversal of 21450035212561 is 16521253005412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20248065046225 + 1201970166336 = 4499785^2 + 1096344^2 .

It is a cyclic number.

It is not a de Polignac number, because 21450035212561 - 2¹³ = 21450035204369 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21450035212561.

It is not a weakly prime, because it can be changed into another prime (21450035212061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10725017606280 + 10725017606281.

It is an arithmetic number, because the mean of its divisors is an integer number (10725017606281).

Almost surely, 2^{21450035212561} is an apocalyptic number.

It is an amenable number.

21450035212561 is a deficient number, since it is larger than the sum of its proper divisors (1).

21450035212561 is an equidigital number, since it uses as much as digits as its factorization.

21450035212561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72000, while the sum is 37.

Adding to 21450035212561 its reverse (16521253005412), we get a palindrome (37971288217973).

The spelling of 21450035212561 in words is "twenty-one trillion, four hundred fifty billion, thirty-five million, two hundred twelve thousand, five hundred sixty-one".