21390363 has 6 divisors (see below), whose sum is σ = 30897204. Its totient is φ = 14260236.

The previous prime is 21390337. The next prime is 21390377. The reversal of 21390363 is 36309312.

21390363 is a `hidden beast` number, since 213 + 90 + 363 = 666.

It is not a de Polignac number, because 21390363 - 2²⁰ = 20341787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21390163) 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 5 ways as a sum of consecutive naturals, for example, 1188345 + ... + 1188362.

It is an arithmetic number, because the mean of its divisors is an integer number (5149534).

Almost surely, 2^21390363 is an apocalyptic number.

21390363 is a deficient number, since it is larger than the sum of its proper divisors (9506841).

21390363 is a wasteful number, since it uses less digits than its factorization.

21390363 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2376713 (or 2376710 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 27.

The square root of 21390363 is about 4624.9716755889. The cubic root of 21390363 is about 277.5914283592.

Adding to 21390363 its reverse (36309312), we get a palindrome (57699675).

The spelling of 21390363 in words is "twenty-one million, three hundred ninety thousand, three hundred sixty-three".