21386533 has 12 divisors (see below), whose sum is σ = 25792480. Its totient is φ = 17323200.

The previous prime is 21386531. The next prime is 21386557. The reversal of 21386533 is 33568312.

It is not a de Polignac number, because 21386533 - 2¹ = 21386531 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21386495 and 21386504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21386531) 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 11 ways as a sum of consecutive naturals, for example, 53133 + ... + 53533.

Almost surely, 2^21386533 is an apocalyptic number.

It is an amenable number.

21386533 is a deficient number, since it is larger than the sum of its proper divisors (4405947).

21386533 is an frugal number, since it uses more digits than its factorization.

21386533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 828 (or 427 counting only the distinct ones).

The product of its digits is 12960, while the sum is 31.

The square root of 21386533 is about 4624.5576004630. The cubic root of 21386533 is about 277.5748595484.

The spelling of 21386533 in words is "twenty-one million, three hundred eighty-six thousand, five hundred thirty-three".