21436513 has 4 divisors (see below), whose sum is σ = 24498880. Its totient is φ = 18374148.

The previous prime is 21436501. The next prime is 21436517. The reversal of 21436513 is 31563412.

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 not a de Polignac number, because 21436513 - 2⁹ = 21436001 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21436517) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1531173 + ... + 1531186.

It is an arithmetic number, because the mean of its divisors is an integer number (6124720).

Almost surely, 2^21436513 is an apocalyptic number.

It is an amenable number.

21436513 is a deficient number, since it is larger than the sum of its proper divisors (3062367).

21436513 is an equidigital number, since it uses as much as digits as its factorization.

21436513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3062366.

The product of its digits is 2160, while the sum is 25.

The square root of 21436513 is about 4629.9582071548. The cubic root of 21436513 is about 277.7909207233.

Adding to 21436513 its reverse (31563412), we get a palindrome (52999925).

The spelling of 21436513 in words is "twenty-one million, four hundred thirty-six thousand, five hundred thirteen".