21053015 has 16 divisors (see below), whose sum is σ = 26042016. Its totient is φ = 16329600.

The previous prime is 21053009. The next prime is 21053017. The reversal of 21053015 is 51035012.

It is not a de Polignac number, because 21053015 - 2¹⁰ = 21051991 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21052984 and 21053002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053017) 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 15 ways as a sum of consecutive naturals, for example, 38645 + ... + 39185.

It is an arithmetic number, because the mean of its divisors is an integer number (1627626).

Almost surely, 2^21053015 is an apocalyptic number.

21053015 is a deficient number, since it is larger than the sum of its proper divisors (4989001).

21053015 is a wasteful number, since it uses less digits than its factorization.

21053015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770.

The product of its (nonzero) digits is 150, while the sum is 17.

The square root of 21053015 is about 4588.3564595615. The cubic root of 21053015 is about 276.1243882015.

Adding to 21053015 its reverse (51035012), we get a palindrome (72088027).

The spelling of 21053015 in words is "twenty-one million, fifty-three thousand, fifteen".