21053513 has 6 divisors (see below), whose sum is σ = 22797774. Its totient is φ = 19433856.

The previous prime is 21053503. The next prime is 21053521. The reversal of 21053513 is 31535012.

It can be written as a sum of positive squares in 3 ways, for example, as 595984 + 20457529 = 772^2 + 4523^2 .

It is not a de Polignac number, because 21053513 - 2¹⁰ = 21052489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21053503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 62120 + ... + 62457.

It is an arithmetic number, because the mean of its divisors is an integer number (3799629).

Almost surely, 2^21053513 is an apocalyptic number.

It is an amenable number.

21053513 is a deficient number, since it is larger than the sum of its proper divisors (1744261).

21053513 is a wasteful number, since it uses less digits than its factorization.

21053513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124603 (or 124590 counting only the distinct ones).

The product of its (nonzero) digits is 450, while the sum is 20.

The square root of 21053513 is about 4588.4107270383. The cubic root of 21053513 is about 276.1265653855.

Adding to 21053513 its reverse (31535012), we get a palindrome (52588525).

The spelling of 21053513 in words is "twenty-one million, fifty-three thousand, five hundred thirteen".