21437513 has 4 divisors (see below), whose sum is σ = 21461760. Its totient is φ = 21413268.

The previous prime is 21437501. The next prime is 21437531. The reversal of 21437513 is 31573412.

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 21437513 - 2¹² = 21433417 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21437573) 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, 10745 + ... + 12582.

It is an arithmetic number, because the mean of its divisors is an integer number (5365440).

Almost surely, 2^21437513 is an apocalyptic number.

It is an amenable number.

21437513 is a deficient number, since it is larger than the sum of its proper divisors (24247).

21437513 is an equidigital number, since it uses as much as digits as its factorization.

21437513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24246.

The product of its digits is 2520, while the sum is 26.

The square root of 21437513 is about 4630.0661982309. The cubic root of 21437513 is about 277.7952402474.

The spelling of 21437513 in words is "twenty-one million, four hundred thirty-seven thousand, five hundred thirteen".