21360813 has 8 divisors (see below), whose sum is σ = 29719488. Its totient is φ = 13621344.

The previous prime is 21360811. The next prime is 21360817. The reversal of 21360813 is 31806312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21360813 - 2¹ = 21360811 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21360811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 154720 + ... + 154857.

It is an arithmetic number, because the mean of its divisors is an integer number (3714936).

Almost surely, 2^21360813 is an apocalyptic number.

21360813 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21360813 is a deficient number, since it is larger than the sum of its proper divisors (8358675).

21360813 is a wasteful number, since it uses less digits than its factorization.

21360813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 309603.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21360813 is about 4621.7759573567. The cubic root of 21360813 is about 277.4635420004.

The spelling of 21360813 in words is "twenty-one million, three hundred sixty thousand, eight hundred thirteen".