21150521 has 4 divisors (see below), whose sum is σ = 24172032. Its totient is φ = 18129012.

The previous prime is 21150491. The next prime is 21150523. The reversal of 21150521 is 12505112.

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 21150521 - 2¹⁸ = 20888377 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21150521.

It is not an unprimeable number, because it can be changed into a prime (21150523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1510745 + ... + 1510758.

It is an arithmetic number, because the mean of its divisors is an integer number (6043008).

Almost surely, 2^21150521 is an apocalyptic number.

It is an amenable number.

21150521 is a deficient number, since it is larger than the sum of its proper divisors (3021511).

21150521 is an equidigital number, since it uses as much as digits as its factorization.

21150521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3021510.

The product of its (nonzero) digits is 100, while the sum is 17.

The square root of 21150521 is about 4598.9695584989. The cubic root of 21150521 is about 276.5500172752.

Adding to 21150521 its reverse (12505112), we get a palindrome (33655633).

The spelling of 21150521 in words is "twenty-one million, one hundred fifty thousand, five hundred twenty-one".