21154505 has 8 divisors (see below), whose sum is σ = 26721600. Its totient is φ = 16032816.

The previous prime is 21154489. The next prime is 21154519. The reversal of 21154505 is 50545112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21154505 - 2⁴ = 21154489 is a prime.

It is a Curzon number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 111245 + ... + 111434.

It is an arithmetic number, because the mean of its divisors is an integer number (3340200).

Almost surely, 2^21154505 is an apocalyptic number.

It is an amenable number.

21154505 is a deficient number, since it is larger than the sum of its proper divisors (5567095).

21154505 is a wasteful number, since it uses less digits than its factorization.

21154505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222703.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 21154505 is about 4599.4026786095. The cubic root of 21154505 is about 276.5673802218.

Adding to 21154505 its reverse (50545112), we get a palindrome (71699617).

The spelling of 21154505 in words is "twenty-one million, one hundred fifty-four thousand, five hundred five".