21154513 has 4 divisors (see below), whose sum is σ = 21470320. Its totient is φ = 20838708.

The previous prime is 21154489. The next prime is 21154519. The reversal of 21154513 is 31545112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21154513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21154519) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 157803 + ... + 157936.

It is an arithmetic number, because the mean of its divisors is an integer number (5367580).

Almost surely, 2^21154513 is an apocalyptic number.

It is an amenable number.

21154513 is a deficient number, since it is larger than the sum of its proper divisors (315807).

21154513 is an equidigital number, since it uses as much as digits as its factorization.

21154513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315806.

The product of its digits is 600, while the sum is 22.

The square root of 21154513 is about 4599.4035482875. The cubic root of 21154513 is about 276.5674150850.

Adding to 21154513 its reverse (31545112), we get a palindrome (52699625).

The spelling of 21154513 in words is "twenty-one million, one hundred fifty-four thousand, five hundred thirteen".