21521013 has 8 divisors (see below), whose sum is σ = 29470368. Its totient is φ = 13959504.

The previous prime is 21521011. The next prime is 21521033. The reversal of 21521013 is 31012512.

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

It is not a de Polignac number, because 21521013 - 2¹ = 21521011 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21520983 and 21521001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521011) 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 7 ways as a sum of consecutive naturals, for example, 96831 + ... + 97052.

It is an arithmetic number, because the mean of its divisors is an integer number (3683796).

Almost surely, 2^21521013 is an apocalyptic number.

It is an amenable number.

21521013 is a deficient number, since it is larger than the sum of its proper divisors (7949355).

21521013 is a wasteful number, since it uses less digits than its factorization.

21521013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193923.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21521013 is about 4639.0745844403. The cubic root of 21521013 is about 278.1554476282.

Adding to 21521013 its reverse (31012512), we get a palindrome (52533525).

The spelling of 21521013 in words is "twenty-one million, five hundred twenty-one thousand, thirteen".