21360961 has 4 divisors (see below), whose sum is σ = 21764052. Its totient is φ = 20957872.

The previous prime is 21360943. The next prime is 21360967. The reversal of 21360961 is 16906312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17901361 + 3459600 = 4231^2 + 1860^2 .

It is a cyclic number.

It is not a de Polignac number, because 21360961 - 2¹¹ = 21358913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21360967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 201466 + ... + 201571.

It is an arithmetic number, because the mean of its divisors is an integer number (5441013).

Almost surely, 2^21360961 is an apocalyptic number.

It is an amenable number.

21360961 is a deficient number, since it is larger than the sum of its proper divisors (403091).

21360961 is an equidigital number, since it uses as much as digits as its factorization.

21360961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 403090.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 21360961 is about 4621.7919684901. The cubic root of 21360961 is about 277.4641828079.

The spelling of 21360961 in words is "twenty-one million, three hundred sixty thousand, nine hundred sixty-one".