21384537 has 8 divisors (see below), whose sum is σ = 28539840. Its totient is φ = 14242800.

The previous prime is 21384533. The next prime is 21384613. The reversal of 21384537 is 73548312.

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

It is not a de Polignac number, because 21384537 - 2² = 21384533 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 21384498 and 21384507.

It is not an unprimeable number, because it can be changed into a prime (21384533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1164 + ... + 6642.

It is an arithmetic number, because the mean of its divisors is an integer number (3567480).

Almost surely, 2^21384537 is an apocalyptic number.

It is an amenable number.

21384537 is a deficient number, since it is larger than the sum of its proper divisors (7155303).

21384537 is a wasteful number, since it uses less digits than its factorization.

21384537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6783.

The product of its digits is 20160, while the sum is 33.

The square root of 21384537 is about 4624.3417910012. The cubic root of 21384537 is about 277.5662239480.

The spelling of 21384537 in words is "twenty-one million, three hundred eighty-four thousand, five hundred thirty-seven".