21360649 has 2 divisors, whose sum is σ = 21360650. Its totient is φ = 21360648.

The previous prime is 21360641. The next prime is 21360659. The reversal of 21360649 is 94606312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11343424 + 10017225 = 3368^2 + 3165^2 .

It is a cyclic number.

It is not a de Polignac number, because 21360649 - 2³ = 21360641 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21360649.

It is not a weakly prime, because it can be changed into another prime (21360641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10680324 + 10680325.

It is an arithmetic number, because the mean of its divisors is an integer number (10680325).

Almost surely, 2^21360649 is an apocalyptic number.

It is an amenable number.

21360649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21360649 is an equidigital number, since it uses as much as digits as its factorization.

21360649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21360649 is about 4621.7582152250. The cubic root of 21360649 is about 277.4628319129.

The spelling of 21360649 in words is "twenty-one million, three hundred sixty thousand, six hundred forty-nine".