21323505 has 32 divisors (see below), whose sum is σ = 40255488. Its totient is φ = 9432000.

The previous prime is 21323503. The next prime is 21323509. The reversal of 21323505 is 50532312.

It is not a de Polignac number, because 21323505 - 2¹ = 21323503 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21323503) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21 + ... + 6530.

It is an arithmetic number, because the mean of its divisors is an integer number (1257984).

Almost surely, 2^21323505 is an apocalyptic number.

It is an amenable number.

21323505 is a deficient number, since it is larger than the sum of its proper divisors (18931983).

21323505 is a wasteful number, since it uses less digits than its factorization.

21323505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6597.

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21323505 is about 4617.7380826548. The cubic root of 21323505 is about 277.3019120372.

Adding to 21323505 its reverse (50532312), we get a palindrome (71855817).

The spelling of 21323505 in words is "twenty-one million, three hundred twenty-three thousand, five hundred five".