21297885361 has 2 divisors, whose sum is σ = 21297885362. Its totient is φ = 21297885360.

The previous prime is 21297885353. The next prime is 21297885377. The reversal of 21297885361 is 16358879212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21141160000 + 156725361 = 145400^2 + 12519^2 .

It is a cyclic number.

It is not a de Polignac number, because 21297885361 - 2³ = 21297885353 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21297885299 and 21297885308.

It is not a weakly prime, because it can be changed into another prime (21297885341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10648942680 + 10648942681.

It is an arithmetic number, because the mean of its divisors is an integer number (10648942681).

Almost surely, 2^21297885361 is an apocalyptic number.

It is an amenable number.

21297885361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21297885361 is an equidigital number, since it uses as much as digits as its factorization.

21297885361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1451520, while the sum is 52.

The spelling of 21297885361 in words is "twenty-one billion, two hundred ninety-seven million, eight hundred eighty-five thousand, three hundred sixty-one".