21388535 has 8 divisors (see below), whose sum is σ = 29332896. Its totient is φ = 14666400.

The previous prime is 21388529. The next prime is 21388541. The reversal of 21388535 is 53588312.

It is an interprime number because it is at equal distance from previous prime (21388529) and next prime (21388541).

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

It is not a de Polignac number, because 21388535 - 2¹⁰ = 21387511 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 611101 = 21388535 / (2 + 1 + 3 + 8 + 8 + 5 + 3 + 5).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21388495 and 21388504.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 305516 + ... + 305585.

It is an arithmetic number, because the mean of its divisors is an integer number (3666612).

Almost surely, 2^21388535 is an apocalyptic number.

21388535 is a deficient number, since it is larger than the sum of its proper divisors (7944361).

21388535 is an equidigital number, since it uses as much as digits as its factorization.

21388535 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 611113.

The product of its digits is 28800, while the sum is 35.

The square root of 21388535 is about 4624.7740485347. The cubic root of 21388535 is about 277.5835205677.

The spelling of 21388535 in words is "twenty-one million, three hundred eighty-eight thousand, five hundred thirty-five".