21236545 has 8 divisors (see below), whose sum is σ = 27800640. Its totient is φ = 15444720.

The previous prime is 21236491. The next prime is 21236561. The reversal of 21236545 is 54563212.

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

It is not a de Polignac number, because 21236545 - 2¹⁷ = 21105473 is a prime.

It is an alternating number because its digits alternate between even and odd.

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, 193005 + ... + 193114.

It is an arithmetic number, because the mean of its divisors is an integer number (3475080).

Almost surely, 2^21236545 is an apocalyptic number.

It is an amenable number.

21236545 is a deficient number, since it is larger than the sum of its proper divisors (6564095).

21236545 is a wasteful number, since it uses less digits than its factorization.

21236545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386135.

The product of its digits is 7200, while the sum is 28.

The square root of 21236545 is about 4608.3125979039. The cubic root of 21236545 is about 276.9244408072.

Adding to 21236545 its reverse (54563212), we get a palindrome (75799757).

It can be divided in two parts, 2123 and 6545, that added together give a palindrome (8668).

The spelling of 21236545 in words is "twenty-one million, two hundred thirty-six thousand, five hundred forty-five".